Thursday, December 30, 2010

Back to OG12 Quant

Wohkay! Seems like I've been out of touch with OG type Math questions for too long.
Did 20 PS and 20 DS questions (timed) today.
Got 4 wrong in PS and...wait for it...9 wrong in DS! Eeeks!
Gotta review and get back to official questions! Good thing I have only the medium-difficult questions remaining... :)

GMAT love to the rest of you! Hope you're studying hard for the next 72 hours...to be able to party tomorrow night without guilt! :)

Tuesday, December 28, 2010

Practice Test #5 (#3 in second round)

Got a 670 (Q47 V35) score on PowerPrep#1. Had a major pacing problem on verbal, had to guess atleast 4-5 questions randomly in the end. No repeats on Quant. but did encounter around 1 CR, 1-2 RC from OG12. But had to rework these questions cos they were difficult/long ones anyway, so don't think it skewed my score. Normally I finish Verbal with time left on my hands, but I think i got really tired - did AWA sections also.
I plan on completing leftover OG12 questions by 31st Dec and give 2 more GMATClub Math tests on 1st Jan. I am NOT doing any more questions from Grockit, because I felt I had seen similar questions on Grockit that I saw on PowerPrep today, or questions that just really helped me figure out the answer quickly.

Anyone think I should buy PowerScore CR bible? Yet to look at my accuracy on PowerPrep so I'll update in the evening once i'm through putting in everything in my error log.
Feeling good with the Q47 though...looks like practice really helps. And I'm confident that i have a large potential to increase my verbal score...so i'm hoping for the best!

Saturday, December 25, 2010

CP #23

From GMATClub.com's m#05:

4. Two watermelons, A and B, are on sale. Watermelon A has a circumference of 6 inches; watermelon B, 5 inches. If the price of watermelon A is 1.5 times the price of watermelon B, which watermelon is a better buy?
(Assume that the two watermelons are spheres).
(C) 2008 GMAT Club - [t]m05#4[/t]
• A
• B
• Neither
• Both
• Impossible to determine

Approach 1:
Value = Volume / Price
The volume is proportional to radius^3 and the circumference is proportional to the radius. Increasing the circumference by 6/5 = 20% increases the volume by 1.2^3 = 1.728 (72.8%) and increases the price by 50%.
The increase in value of Watermelon A is 1.728 / 1.5 = 15.3% .

GMATClub m#05

Again got 26/37 correct. This time percentile ranking was 45.2% 60.1% (for some reason, my percentile ranking just changed in that last 1 hour) - haha, I guess I did get a little better.

But I ran out of time on this test - had to pause in order to finish it. Yes, concentration was wavering.

Got frustrated with Probability and P&C questions - I really need to understand this topic before attempting any more questions. Maybe I should ask my school Math tutor if he'd help me out with this topic??? I'm seriously considering it now.

Incorrect Qs Summary:
Topic - No. of questions incorrect
Geo - 1
TSD - 1
Probability/P&C - 2
Inequalities - 1
Number Properties/Is x divisible by y type - 6!

Hmmm...

CP #22

GMATClub m#02 test:

Is $x \gt y^2$ ?
1. $x \gt y + 5$
2. $x^2 - y^2 = 0$
(C) 2008 GMAT Club - [t]m02#19[/t]
• Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient
• Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient
• BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient
• EACH statement ALONE is sufficient
• Statements (1) and (2) TOGETHER are NOT sufficient
Statement (1) by itself is insufficient. Consider $(x,y)=(5, -1)$ or $(5, -3)$ .
Statement (2) by itself is insufficient. Consider $(x,y)=(\frac{1}{2}, \frac{1}{2})$ or $(2, 2)$ .
Statements (1) and (2) combined are sufficient. The absolute values of $x$ and $y$ are equal and $x \gt y$ , implying that $x$ is positive and $y$ is negative. Therefore, $x \gt y^2$ is false.

Friday, December 24, 2010

GMATClub m#02

26/37 correct on GMATClub's m#02. My percentile is 31.1% :p

Managed to finish the test on time. Some questions were pretty easy, some I answered incorrectly due to silly mistakes, and some I thought I got but apparently I didn't. Pretty good mix in terms of difficulty, although I got a little annoyed with the large number of questions from Number Properties.

Any comments on how this score is at this stage of studying? And post having worked on Time & Work (1 qs in the test - which i got wrong!), Time/Speed & Distance (0 qs. on test) and Averages/Mix/Allig (1-2 qs. on test)???

Classy Career Girl's post

http://www.classycareergirl.com/2010/12/10-tips-for-young-career-professionals.html

Awesome! Very relevant tips. I believe in pretty much all of them.

Thursday, December 23, 2010

CR Help by Farbood

Going through free CR lessons by Grockit here. I think they're nice lessons, but I could be biased. Anyone else think Farbood Nivi is totally hot? ;)

Did some more Work questions today. Will practice some more TSD questions, and then go through FCs.

Wednesday, December 22, 2010

Planning & Executing

Got it, well...kind of. Alligations that it. Managed to find my old TIME notes, and went through quite a few questions from the book. Have a much better hang of averages too.

To Do:
1. Have to do some more questions from that book for DST & Work.
2. 19 tables (yes, still not done...should probably get to it NOW). FYI, learning my tables has really helped in calculating faster :) I loveeeee it!
3. Go through my FCs.
Am giving practice tests from GMATClub.com on Friday afternoon/evening and Saturday morning (free access to all tests!). So I must revise all this math stuff. Friday morning, I might do some Verbal if I have time so that my Saturday morning test can be a Verbal one.

Sunday morning (26th) is TEST DAY. Someone might lend me Kaplan practice tests, so will def give one of those.

Happy studying till then!

Tuesday, December 21, 2010

A Mixture of Topics

Worked through some Averages & Mixtures problems from TIME material. Didn't really understand Alligations. Also managed to revise Interest problems.

Off to start questions from CAT Prep on pagalguy.com

Other things I wish to dabble in today:
Grockit.com / Tenaday.co.in / 19 tables / a lot more math practice!

Monday, December 20, 2010

42 days to go

Did the chapter on Time & Work from TIME (CAT) material. :) Feel a lot more confident about it!
Tomorrow I'll dig into averages/mixtures/alligations and then onto practicing all 3 topics (1st one being Time, Speed & Distance) from Pagalguy.com's CAT Prep questions.

I'm practicing Quant from Grockit.com randomly. Good way to stay in touch with all Math topics.

Not really in the mood to practice verbal at the moment. Want to get great at Math, or atleast confident about all the stuff - I knew at some point and have forgotten along the way/ I can do.

Have done my tables from 13-18, still need to do 19 and revise all of it. Then onto squares and cubes and fractions (to decimals). :)

I'm feeling happier by the day!

Off to catch up on Psych episodes now. :) hehe.

Saturday, December 18, 2010

CP #21

A train travels at an average speed of 200 km/hr without any stoppages. However, its average speed decreases to 120 km/hr on account of stoppages. On an average, how many minutes per hour does the train stop?

Options: 12, 18, 20, 24 minutes.

OA: 24 minutes

Solution:
You have to find out how many minuter PER HOUR does the train stop.
So, use T = 1 hour.
In 1 hour, the train travels 200 km.
If the distance travelled reduces to 120 km, how much time does it take the train to travel a distance of 120 km? The remaining time (1 hour - time taken to travel 120 km) will give us the stoppage time (per hour).
S = D / T
200 = 120 / T
T = 3/5 hour = 3/5 * 60 mins = 36 mins

So the train has taken 36 mins to travel 120 km in 1 hour. This means that the train stopped for how many minutes? 60 - 36 = 24 mins of stoppage time per hour.

Easing My Way In

Spent quite some time on Grockit yesterday, doing Math problems. Just trying to ease myself back into the groove.

My official leave from work starts today. 1 month and 15 days to go for my date with the GMAT.

Today's To Do List:
1. Modifiers - MGMAT SC (revise chapter)
2. Math practice from Grockit
3. Begin theory review of TSD from TIME
4. Revise Speed Math strategies you've learnt till now
5. Do 1 new Speed Math chapter
6. Tables from 15 - 19 (yup, all...!)

I was also thinking today, I'm going to feel so odd not working for the next 1.5 months! I'm already missing work :( . Yes, I love my workplace, and I love the work we do, and I love helping someone out to finish a deadline, etc etc... I miss my people!

Wednesday, December 15, 2010

To Apply in Round 3 or Round 1 in 2011?

HBS: 31st March
Stanford GSB: 6th April
Chicago Booth: 13th April

Hmmm...I'm contemplating applying to these schools in Round 3. Anyone else think it's a good idea? Not sure of how I'll convince my bosses to write my recommendations though. They want me to apply in for Sept 2012 intake. Hmmm...might be a better option too since their recommendation letters will have a lot more positive stuff to stay by Round 1 of next admission intake session. Thoughts anyone???

Multiplication Worksheet

Found a great website for practicing Multiplication tables (am currently learning my tables from 13-19), and for putting to practice all those Speed Math techniques I've learnt!

It's called MathsIsFun.com and I love the worksheets they have here!

Thought I should share this great practice spot to all my fellow Gmatters!

Monday, December 13, 2010

The Day I Score an 800 has been booked!

I booked my GMAT date. It's on the 1st of Feb. Taking 1.5 month's leave from office for the test, so it's now or never baby! :)
So excited and relieved to have booked it. 250 USD charge has been initiated on my credit card...! :)

Over the next 2 weeks, I'm going to:
1. finish OG11
2. go through Pronouns, Modifiers & Verbs from MGMAT SC and GMATClub's Grammar book
3. work on DST, Work and Mixtures/Averages chapters from TIME material
4. learn tables from 13-19 (13 & 14 done), learn squares & cubes & fractions to decimals
5. go through some Speed Math chapters
6. go through all my flash cards

24th Dec - Give free GMATClub.com tests (one Q, one V; or 2 Q)
27th Dec - Give GMATPrep #1.

Friday, November 26, 2010

CP #20

What is the number of integers from 1 to 1000 (inclusive) that are divisible by neither 11 nor by 35?
(C) 2008 GMAT Club - [t]m07#14[/t]
• 884
• 890
• 892
• 910
• 945
To count the number of integers from 1 to $N$ (inclusive) that are divisible by $x$ , find the value of $\frac{N}{x}$ . Use only the integer part of the resulting number. Based on the formula, the number of integers divisible by 11 is $\frac{1000}{11} = 90.9 = 90$ (even though the result could be rounded off to 91, use 90). In the same way, the number of the integers divisible by 35 is $\frac{1000}{35} = 28.57 = 28$ .
Subtract the number of integers that are divisible by both 11 and 35, so that they are not counted twice.
Therefore, $\frac{1000}{11} + \frac{1000}{35} - \frac{1000}{11*35} = 90 + 28 - 2 = 116$ .
$1000-116 = 884$ .

My answer was right. Wanted to keep this here to understand why they've used 1000/ 11*35. What I did was calculate 33*11 and 33*11*2 and saw that both are under 1000 and then counted 2. I should know this other method too.

CP #19

If Ben were to lose the championship, Mike would be the winner with a probability of $\frac{1}{4}$ , and Rob - $\frac{1}{3}$ . If the probability of Ben winning is $\frac{1}{7}$ , what is the probability that either Mike or Rob will win the championship (there can be only one winner)?
(C) 2008 GMAT Club - [t]m07#12[/t]
• $\frac{1}{12}$
• $\frac{1}{7}$
• $\frac{1}{2}$
• $\frac{7}{12}$
• $\frac{6}{7}$
The probability of Mike or Rob winning, conditional on Ben losing, is $\frac{1}{4} + \frac{1}{3}$ or $\frac{7}{12}$ . The unconditional probability (to take into consideration the probability of Ben winning) is then $(1-\frac{1}{7}) * \frac{7}{12} = \frac{6}{7} * \frac{7}{12} = \frac{1}{2}$ .

I have calculated it very differently and gotten 5/14 for an answer.

CP

A contractor estimated that his 10-man crew could complete the construction in 110 days if there was no rain. (Assume the crew does not work on any rainy day and rain is the only factor that can deter the crew from working). However, on the 61-st day, after 5 days of rain, he hired 6 more people and finished the project early. If the job was done in 100 days, how many days after day 60 had rain?
(C) 2008 GMAT Club - [t]m07#6[/t]
• 4
• 5
• 6
• 7
• 8
•
•
•
• The amount of work in man-hours is: $110 * 10 = 1100$ mh. After 60 days with 5 days of rain (55 net days) the crew of 10 had completed 550 mh of work, and had 550 mh more to go. Of the remaining 40 days, $x$ were raining. The last 550 mh were completed by 16 men: $(40 - x) * 16 = 550$ , and $x = 5.625$ . Round the number of rainy days down to 5 as with 6 rainy days the crew would have worked less than 550 mh and not have completed the job.

Tuesday, November 23, 2010

CR update

So after going through all these CR notes on the net, I tried 3 questions from OG12 (not too many left to choose from...yey!) - one of each type (S, W & A). Got the assumption question wrong, the others were right. Hmmm...going to practice slowly (i.e. identify question type, conclusion, premise(s) and imagine any linking assumptions) from my BTG account.

Wish me luck!

Edit: Tried a few BTG questions, and some other questions online...Hmmm...still not feeling satisfied, although I do have a methodical way of answering the questions now. *sigh*
I should go through other question types, and then do the remaining CR questions from OG12, right?

Monday, November 22, 2010

Improving first, then moving forward.

Did not finish OG12. Reason is that I was going through my error log and realised I was getting certain types of questions consistently wrong in CR and SC - thought I should work on them. Posted it on GMATClub.com to see if anyone could give me some tips on improving my accuracy.

For Quant, I've mainly been making silly mistakes. Also, I haven't gone through my FCs in really long so have forgotten some stuff like Compound Interest formula and how to calculate SD. Need to do that.
In addition, I've been getting Triangles questions wrong - so plan on going through this series on Triangles tricks.

---
Have spent most of today working on getting my basics right in CR. Will post an update soon.

PS. Will take a month off from work before the GMAT because the way my work works, THIS is not going to work out! :) I've spoken to my boss and he said it'll not be an issue. So I am taking GMAT end of Jan, hopefully by 27th Jan 2011. I want to get my 800 already. :)

Friday, November 12, 2010

Have been doing OG12 questions - 50 in one sitting. Has been going on slowly, but surely. Plan is to finish OG12 by next Thursday (6 more days). Have about half of OG left. Then I'll either work on my areas of weakness (as determined by error log analysis), or work through OG Quant & Verbal supplements (will have to buy them).

Work has been slow, and idle for the last 2 weeks. I wasn't expecting it at all, so have not made full use of it :(
But, things are looking up now in terms of studying so very happy :)

I love my life when I study, work, dance and do my chores consistently!!! :)

"Do or do not. There is no try."

Thursday, November 4, 2010

CP#17

Question (from MGMAT Practice Test #1)
For positive integer k, is the expression (k + 2)(k2 + 4k + 3) divisible by 4?

(1) k is divisible by 8.

 (2) k + 1 3 is an odd integer.

Solution
The quadratic expression k2 + 4k + 3 can be factored to yield (k + 1)(k + 3). Thus, the expression in the question stem can be restated as (k + 1)(k + 2)(k + 3), or the product of three consecutive integers. This product will be divisible by 4 if one of two conditions are met:

If k is odd, both k + 1 and k + 3 must be even, and the product (k + 1)(k + 2)(k + 3) would be divisible by 2 twice. Therefore, if k is odd, our product must be divisible by 4.

If k is even, both k + 1 and k + 3 must be odd, and the product (k + 1)(k + 2)(k + 3) would be divisible by 4 only if k + 2, the only even integer among the three, were itself divisible by 4.

The question might therefore be rephrased “Is k odd, OR is k + 2 divisible by 4?” Note that a ‘yes’ to either of the conditions would suffice, but to answer 'no' to the question would require a ‘no’ to both conditions.

(1) SUFFICIENT: If k is divisible by 8, it must be both even and divisible by 4. If k is divisible by 4, k + 2 cannot be divisible by 4. Therefore, statement (1) yields a definitive ‘no’ to both conditions in our rephrased question; k is not odd, and k + 2 is not divisible by 4.

(2) INSUFFICIENT: If k + 1 is divisible by 3, k + 1 must be an odd integer, and k an even integer. However, we do not have sufficient information to determine whether k or k + 2 is divisible by 4.

Query
I think the answer is D. In Statement (2), for (k+1)/3 to be an odd INTEGER, k+1 has to be divisible by 3. Also, k must be even. Therefore, k could be 2,8,... And if k is an even integer, (k + 1)(k + 2)(k + 3) will not be divisible by 4 for any of these values of k. Therefore, Statement (2) also gives us the answer. Please tell me where I'm going wrong.

CP #16 - have not understood why not my way?

Question (from MGMAT Practice Test #1)
In a room filled with 7 people, 4 people have exactly 1 sibling in the room and 3 people have exactly 2 siblings in the room. If two individuals are selected from the room at random, what is the probability that those two individuals are NOT siblings?

Solution
We are told that 4 people have exactly 1 sibling. This would account for 2 sibling relationships (e.g. AB and CD). We are also told that 3 people have exactly 2 siblings. This would account for another 3 sibling relationships (e.g. EF, EG, and FG). Thus, there are 5 total sibling relationships in the group.

Additionally, there are (7 x 6)/2 = 21 different ways to chose two people from the room.

Therefore, the probability that any 2 individuals in the group are siblings is 5/21. The probability that any 2 individuals in the group are NOT siblings = 1 – 5/21 = 16/21.

Wednesday, November 3, 2010

A Side Note to my Last Post

Some other reasons why you might want to buy BTG questions:
1. The cost: $99 The cost till 15th November:$49!
2. BTG is giving away 3 iPads! All Free and Premium users of Practice Questions who sign up by 15th November will be eligible to win.
So even if you are not sure of buying the product, atleast sign up for the free questions and you might just win an iPad!
3. 30-Day Money Back Guarantee. Seriously, it doesn't get any better than this. :)

Happy Gmatting!

Tuesday, November 2, 2010

Yes You Can! With the *new* BTG questions.

Want to practice only SC questions today? Have time to do only 10? Yes you can!
Have you mastered the fundamentals of Probability and want to target today's practice session only on 700+ level questions on the topic? Yes you can!
After a review of your error log, do you realize that you really need to work on those Weaken type Verbal questions? Across CR and RC? Yes you can!
Do you always get Integer Properties questions wrong only on the DS section? Have all day to work on it and want an (almost) unlimited supply of questions to be thrown at you till you crack it? Yes you can!
Tired of going through consecutive questions in the Official Guide which are at the same difficulty level? Want a practice session where the questions thrown at you are in an adaptive format? Yes you can!
Have you run out of CAT tests and want to create one of your own? Yes you can!

BTG has managed to create an (almost) perfect product. If you've run out of OG questions, and even CAT tests, this product's for you. [This is an improved product from BTG which is to be released today, November 2nd. It can be found here].

Totally customizable
Every practice quiz you take is totally customizable to your preferences. You can choose which section you want to target (Math or Verbal), which type of question to target (CR, RC, SC, PS, DS) and even the topic of the questions (Idioms, Weaken, Arithmetic...)!
You know what else I love? You can choose the number of questions you want to answer!
Have time only for 10 questions today? Your boss suddenly interrupts you during the 5th question with urgent work? No problem! You can choose to end the practice session there and see your results.
And this part, my fellow readers, is what I call an absolutely brilliant feature - the difficulty level. You have a choice of below 400 questions only, all the way upto 700+ level questions. And, that's not even the most brilliant part. Have you heard of..wait for it...adaptive questions on every quiz?! This one made me super happy!
A timer on the right hand side tells you how much time you've spent on the question during the quiz.

Create a New Test

You can choose to answer 37 Math questions, in an adaptive format. Once you've ended your session, head back to the "Practice" tab and create a session for 41 Verbal questions (adaptive mode). A brand new test has been created! :) You can also randomly pick any topics for the 2 essays from the OG, and you're all set to give a full 4 hour exam at home!

A breakdown of questions on each section
Math -
I found the difficulty level of questions pretty reasonable, not extremely easy and not so difficult that you'd never be able to crack it in 2 minutes (under 3 minutes for the really difficult ones).
Verbal -
Pretty much the same as for Math...

The Video Explanations
A friend of mine wanted to practice some SC questions and wanted me to help him out with understanding where he was going wrong. So I called him over to practice from my Reviewer's account of BTG questions. Once he was done with the questions, I realized I didn't have to say a word to explain his mistakes to him! The video explanations did all the talking! They even taught us a few things we didn't know, such as idioms that I wouldn't have caught if I was trying to explain it to him myself.
The Math explanations are clear, and I didn't find myself requiring any further explanation once the video was over.

Review
The review section is pretty much the same as you'd find in any other similar product. But there are two parts that stand out for me:
First is the colour of the amount of time you've taken to answer the question. The colour is different according to whether you've outpaced others who answered the question, or were slower than them.
The second is the flagging the questions feature. In case you want to review the question again (irrespective of whether you got it right or wrong), you can flag it. What's the point of flagging it, you ask? *sly grin*

Prepare yourself for...

Super-Customization
I was feeling pretty content and happy after having customized my practice session down to the topic of questions I wanted to answer. But before I clicked on the "Start the Session" button, I saw blue text that said "Show more options". More options?
Here they are:
- include questions that I have already answered (after going through 700 questions, are you really going to remember them all?)
- use only flagged questions (yup, include the questions you got right but should still do again)
- only use questions I got wrong (for obvious reasons)
And yes, you can select all 3 at the same time also.

Definitely worth it if you've run out of questions to practice from, or want to customize your practice sessions exactly according to your needs (especially if you want to do this!). I had hoped such a product would come out for OG12 questions (and it's Verbal & Math supplements) so that I could practice questions from those books in an adaptive customizable style. I hope this great effort from BTG gets a similar product out for Official questions soon! :) Till then, enjoy the power and remember, with BTG questions, YES YOU CAN!

PS. BTG is giving me a couple of subscriptions to this new product to give away. While I'm giving some to my friends who're also giving the GMAT soon, I might have 2 accounts left over to give away. So I'll do that on a first come first serve basis. HOWEVER, I will also snoop around and try ensuring that you don't already have an account that's been given away (I have my sources! :p). Once I'm satisfied that you do need one, I'll send you access to it! :)

Saturday, October 30, 2010

Practice Test #4 (#2 in second round)

Just gave MGMAT CAT #1.

Scored a 660 (Q45, V35).

How's that for a first score? Anyone?

Edit: Finished reviewing Quant section. Most of them were careless mistakes, or a result of feeling pressurized due to timing and therefore not going through the question properly (not thoroughly thinking about it). Most of the questions were doable. Learnt some new concepts - hexagons and a little more about probability and combinatorics.

Wednesday, October 27, 2010

The Reviewer

Reviewing all the questions I've got wrong in OG12...most of my Quant questions are careless mistakes. In DS, I forget to thoroughly review Statement II sometimes.

Off to review Verbal now...

PS. I will review a new set of practice questions on 2nd November...stay tuned!

Tuesday, October 26, 2010

Disturbed.

RC accuracy remains intact with 6/6 answers right.

PS - need to review Number Properties (esp Remainders).

DS - accuracy fell massively - 4/10 wrong.

CR - got 2/10 wrong.

Overall, getting better. Feel better. But, need to review old concepts. AND not be disturbed while doing my questions!!!

Also, got access to BTG account as a winner of BTG 100k Challenge! :)

Will also write a review on new & improved BTG premium questions by end of this week!

Stay tuned fellow gmatters!

Sunday, October 24, 2010

OG12 continues

Yes, I was unable to study because of work. What's new. But I've tried to stay in touch.

Reviewed OG12 questions I had done previously, my CR accuracy has gone up - I'm pleasantly surprised.

Also, did about 50 questions from OG12 today - 10 questions of each type. Although I'm only doing Easy & Medium level questions, getting most of them right. Today - got only 1 question wrong out of 50 (an SC idioms error). So not much to review now. :)

I'm giving it this November. All set.

Wednesday, October 20, 2010

I WOOOOOOOOONNNNN!

:) Have won access to BTG Premium Questions!!!!!!!!!!!!!!!!!!!!!! Yayyyyyyyyyyy! Also won some book on Interview Questions by Accepted.com...yayyyyyyyyyyy!

Saturday, September 25, 2010

The beginning of reality.

Started OG12 this morning - 14 PS and 10 CR questions. Got 2 CR questions wrong. And I'm going to get excited every time I get a Verbal question wrong from now on, esp CR. Because if I get an OG question wrong, it will help me learn where I'm going wrong! :)

Also done with Speed Math chapter 9, still going through chapter 10.

Spent some time in office doing questions from BTG's articles. Was fun! :) I need to get back in the groove now, still hoping to get done with GMAT by mid-November. Wish me luck guys, I neeeed it!

Happy Gmatting!

Friday, September 24, 2010

CP #17

Question:

Jane and Thomas are among the 8 people from which a committee of 4 people is to be selected.  How many different possible committees of 4 people can be selected from these 8 people if at least one of either Jane or Thomas is to be selected?

A) 28
B) 46
C) 55
D) 63
E) 70

Method 1 -

The first step in this problem is to recognize that order does not matter.  We must create a committee of four people, but we are not putting these people in any sort of order.  Because order does not matter, we must use the combinations formula, which is n!/[k!(n-k)!], in order to determine the number of possible outcomes.

However, as is the case with most advanced combinations problems, the solution is not as simple as plugging a few numbers into the formula.  Instead, we need to consider exactly what types of outcomes we are looking for.

In this case, we need to select Jane and 3 other people, none of whom are Thomas; Thomas and 3 other people, none of whom are Jane; or Jane, Thomas and 2 other people.  Additionally, we need to note that this is an 'or' situation, which means that we need to add all of these possibilities together.

First, if we select Jane and three others, none of whom are Thomas, we must pick Jane plus 3 out of the remaining 6 people.  Because we can pick any 3 out of the 6, we set n = 6 and k = 3.  When we plug this into the formula it gives us 6!/(3!3!) = 20 (Quick review: 3! = 3 x 2 x 1, 6! = 6 x 5 x 4 x 3 x 2 x 1.)

Next we determine how many ways we can select three people, none of whom are Jane, to go along with Thomas.  This is identical mathematically, thus we end up with 20 in this case too.

Lastly, we determine how many outcomes are possible in which we have Jane, Thomas and 2 others.  We now select 2 out of 6, so n = 6 and k = 2.  6!/(4!2!) = 15.

All we need to do to get the answer is add up all of the possible outcomes.  20 + 20 + 15 = 55, which is the correct answer to this question (C).

Method 2 -

required combinations = total combinations - combinations excluding both Jane and Thomas.

Total combinations = 8c4 = 70

combinations excluding both Jane and Thomas = 6c4 = 15

CP #16

BTG Challenge Question:

How many unique 12-letter "words" can be created using 8 A's and 4 B's such that no 2 B's are adjacent? (For example, the word "ABAABABAAABA" is permissible, but the word "AABBABABAAAA" is not permissible, since it has 2 adjacent B's)

we have 8 A's and 4 B's and we need to figure out how many ARRANGEMENTS are possible such that no two B's are together.

First let us arrange 8 A's. As all are identical we have just one way to arrange them.

Here my advice is to actually write 8 A's on your note pad. Now see my friend we have nine places where 4 B's can go. just count.

_ A _ A _ A _ A _ A _ A _ A _ A _

these 4 places can be chosen in 126 ways. apply combination formula ie 9C4.

Now as all 4 B's are identical we don't need to worry about arranging those 4 B's ( after placing them in four of the nine places.) So, here is your answer friend. i would have further counted for the permutations if the 4 B's were not identical. But as they are identical the answer is 126.

Sunday, September 12, 2010

Practice Test #3...or #1? Last one was in Dec '09.

Have reviewed my diagnostic test, have some verbal doubts which I will put up on BTG or GMATClub forums to get clarity on.

Gave the free Kaplan test this morning on the net. Got a 610 (Q39 V37). Not paying too much attention to the score. Actually found the PS questions very easy, had forgotten how to solve some "types" of questions, which is why I got a few wrong. Not a big deal, will be able to solve those easily by the time the real test arrives. Finished the section with 5 minutes to spare - timing was an issue. There were 2-3 questions of the type where I know how to solve them, just couldn't recall during the test, so I spent too much time on those questions. Finally, I guessed on those questions (which ultimately meant a massive waste of time), and got tensed so I ended up doing the next few questions super fast. But, this test is not typical of the actual test at all. I'm sure of it. A million reasons why. More on that in some other post.
During Verbal, I had to guess on last 2 questions as I ran out of time. Was slow on the section as I was getting easily distracted with the extremely boring content on all the questions. What a lame excuse! :-p A more probable reason is the lack of stamina at the moment, or the fact that I just didn't want to give  a test this morning.

Just putting in my answers in the error log now...later.

Thursday, September 9, 2010

Is Verbal my new weakness?!

Only 2 chapters left to do from MGMAT SC Guide. Have also gone through all Math theory concept review chatpers from Kaplan Premier - mainly the practice sets. Work is also coming along at a good pace.

Am also done with putting in all my Diagnostic test answers in the error log. Difficult task to match all the question categories between different error logs available on the net. Need to work on it, so that I can accurately tell which areas are my weak points. At the moment, Strengthen & Weaken category of CR questions appears to be my weakest link. More on this later...

Now for some non-GMAT, non-MBA, non-work related stuff:
My boyfriend came back to town yesterday after a 9 day trip abroad. :-) That's probably how I've got so much studying done along with work! :-p
Saw a gorgeous top at Zara (Rs 3600) and an amazing dress at Forever New (Rs 5000+)...and I want them both! I know, I know, expensive...but...will probably get the Zara top this weeked...and the dress, won't really have any place to wear it to...so probably won't. But it's such a pretty dress! And it fits me sooo well! *sigh*

Saturday, September 4, 2010

Where's my Excellent?!

Woke up at 5 am and did the Verbal section of OG 12's Diagnostic test. Scored above average across all 3 sections...am very disappointed. Will figure out what I did wrong in a while... :-(

Thursday, September 2, 2010

Manhattan GMAT SC Guide : You're going down.

:-)

Done with Chapters 6, 7 & 8. Made good use of the holiday!

Wednesday, September 1, 2010

One Chapter at a Time

Just got done with MGMAT SC Chapter 5 on Pronouns. Holiday tomorrow so expect to finish off 3 more chapters, and go through the pending MGMAT Math tutorials they have on their website. Will try finishing a 4th chapter from SC guide too. Wish me luckkkkk!

Tuesday, August 31, 2010

Back with SC

I don't think I need to give reasons for my absence except for 1 word - Work.

Anyway, have started MGMAT SC Guide. Done with chapter 1, 2, 3 & 4.

Target GMAT Prep exam date: 31st October, 2010.

Thursday, August 19, 2010

OG 12 Diagnostic - Quant

Scored Excellent in both PS and DS (got 20/24 right in each). Put in my answers in the Error Log. Had to combine an error log and a guide to OG12 to make my error log make sense (will post this on GMATClub once I'm done with OG12 I guess). Apparently, my accuracy in Geometry pulled down my score. And that could be because I studied Geo a couple of weeks before the test, and managed to just put in 2-3 hours of going through my FCs on the night before the test. Still, Geo's my strong point, so not glad to see this.

Will now try the questions I got wrong once again, without looking at the actual answer (although my previous answer choice will be POEd beforehand). Once I'm done, will go through explanations of all the questions I had issues with, and fill in whatever's remaining in the error log.

Wednesday, August 18, 2010

Absolutely Not So Simple

Tried going through GMATClub's chapter on Absolute Value, 'tried' being the key word here.
I thought it was going to simple restate that the absolute value is the distance between two points. However, it took me back to my Class XI days of trying to solve absolute value questions. Damn my sister, she's lost my theory notebook from my tuition days, and now I need to redo all the thinking for this chapter.
It's not as simple as it sounds, need to try my luck again. In other words, bhai samajh mein hi nahi aaya. Probably needs a fresh mind. If it still doesn't work, Aman Chawla to the rescue I guess.

Tuesday, August 17, 2010

47 on Verbal...how do you get a 51?

She scored a 47 on Verbal. Find her debrief here.

Date of Expiry

My access to Kaplan Premier's online quizzes and tests expires on 28th August!!! :-O
I totally forgot about this...damn it! Need to do all the quizzes before it expires. Damn it damn it damn it!

Of Diagnositcs, Parties, and Plans

OG12 Diagnostic Quiz - Quantitative section: DONE.
Since I took the test untimed, it took too much time. Was exhausting. Also had to take a break between PS and DS to finish off some work that came up during that time. So on Saturday, by the time it was 4:30 in the evening, I was exhausted, mentally as well as physically. Before the test, I had managed to go through all my FCs to recall all the concepts I had learnt till then. During the test, I kept Google and my FCs handy, since I did not want to mess up a question cos I forgot a formula. The purpose of the test was just that - to gauge my level of preparedness in terms of my ability to solve a question.

Although the test went well (will put up details on my score and error log as well as CPs later), it was very tiring. Took the rest of the day off from studies - partied at night :-) and stayed over at my cousin's. Didn't look at my books on Sunday and Monday as well.

Have stayed awake post 2 on Saturday, Sunday and Monday night. This has screwed up my sleep schedule just a teeny tiny bit. Will wake up at 5 am tomorrow onwards again. Have a plan ready for the next two weeks. Aim is to give the Verbal section of OG12's diagnostic this Saturday. Not much to prepare for that really. Will start with MGMAT SC guide post that test.

28th August - first Practice test of the season (since the 2 I gave end of last year pretty much don't count now, I guess...). Should it be Princeton Review's CAT #2? Shall be followed by more partying. :-)

Oooh! Also! I'm going to get "The Power" - the new book by Rhonda Byrne. It just keeps getting better, doesn't it?!

Oh, and I guess you'd want this update too. Finally got to read Artemis Fowl's latest book. Was good fun. although I think I might have outgrown it a bit.

Thursday, August 12, 2010

Remainder of today's CPs.

This is the link to Remainder questions. Sriharimurthy's explanations are really good. Good questions to repeat at some later stage! Have understood them for the time being. Should probably note down what I've understood here or elsewhere, so as to not go through the whole thread all over again. Phew. I'm tired now, have solved and understood quite a few challenging questions today!

To Do:
Combinatorics tutorial from MGMAT
Kaplan questions - P&C, Probability, and all the other topics.

CP #15

From GMATClub Math Book Remainders:

If s and t are positive integer such that s/t=64.12, which of the following could be the remainder when s is divided by t?
(A) 2
(B) 4
(C) 8
(D) 20
(E) 45

OA: E

Using the concept,
If you take the decimal portion of the resulting number when you divide by "n", and multiply it to "n", you will get the remainder.
Eg. 8/5 = 1.6
0.6*5 = 3 = remainder

In our question,
0.12*t = R(remainder)
Since R has to be an integer, it must be a multiple of 0.12.
To make the calculation simpler, we multiply both sides by 100.
12*t = 100R

Now, put the value of different Rs in the equation and find which one is perfectly divisible by 12.

i.e. which one of
(A) 200
(B) 400
(C) 800
(D) 2000
(E) 4500
is perfectly divisible by 12 or 3*4.
All are divisible by 4, since they end in 00s.
Only (E) is divisible by 3 also (4+5=9).

CP #14

From GMATClub:

10 business executives and 7 chairmen meet at a conference. If each business executive shakes the hand of every other business executive and every chairman once, and each chairman shakes the hand of each of the business executives but not the other chairmen, how many handshakes would take place?

(A) 144
(B) 131
(C) 115
(D) 90
(E) 45

OA: C
Chairmen shake hands 10*7=70 with business executives times. Business executives shake hands with each other 10 C 2 times or 45 times. The total is 115 .

Why 10C2?

10 business executives shakes hands with other 9 business executives in 10c2 ways = 45 ways
10c2 = 9+8+7+6+5+4+3+2+1 = 45

First executive shakes hands with remaining 9 executives
Second executive shakes hands with remaining 8 executives
Third executive shakes hands with remaining 7 executives
Fourth executive shakes hands with remaining 6 executives
Fifth executive shakes hands with remaining 5 executives
Sixth executive shakes hands with remaining 4 executives
Seventh executive shakes hands with remaining 3 executives
Eighth executive shakes hands with remaining 2 executives
Nineth executive shakes hands with remaining 1 executives
Tenth executive already shakes hands with all 9 executives.

CP #13

From GMATClub's Probability chapter:

Q: There are 5 chairs. Bob and Rachel want to sit such that Bob is always left to Rachel. How many ways it can be done ?
Solution: Because of symmetry, the number of ways that Bob is left to Rachel is exactly 1/2 of all possible ways:
N = 1/2 * 5P2 = 10

Why half?

The Mystery of the Divisor Addition to the Negative Remainder

I have a doubt regarding the formula used for Remainders in GMATClub's Math Book: see Point #6, Eg. #2.

Q. What is the remainder of (20*27) when it is divided by 25?

Note: Rof = remainder of

A. The formula I used is: Rof xy/n = Rof {Rof[(x-n)/n] * Rof[(y-n)/n]} / n

Therefore,  Rof 20*27/25 = Rof {Rof[(20-25)/25] * Rof[(27-25)/25]} / 25
= Rof {Rof[(-5)/25] * Rof[2/25]} / 25
= Rof [(-5 * 2) / 25]
= Rof [(-10) / 25]
= (-10)

But, since the remainder is negative, we add n to it to give us the remainder.
Therefore, Rof 20*27/25 = -10 + n = -10 + 25 = 15.

Why did we add n to the negative remainder?

CP #12

Another one from GMATClub Math Book's Probability chapter.
Given that there are 5 married couples. If we select only 3 people out of 10, what is the probability that none of them are married to each other?

They have given 3 different ways to solve it. All have gone over my head. Help!

CP #11

This one's from the Probability chatper in GMATClub's Math Book.

If the probability of raining on any given day in Atlanta is 40%, what is the probability of raining on exactly 2 days in a 7-day period?

The way I look at it is this:
7 days, out of which on 2 it rains.
2 rain, 2 without rain = 0.4*0.4*0.6*0.6*0.6*0.6*0.6
= (0.4)^2 * (0.6)^5

7C2 * (0.4)^2 * (0.6)^5

I don't understand why the 7C2 is required.

--

Went through the explanation in the chapter itself. It says that, it could rain on Day 1 and 2, or on Day 3 and 7. The sequence changes, although the number of days on which it rained remains the same. This must be factored in to get the correct answer. So other than the probability of it raining on those 2 and 5 days, we must also factor in the possibilites of different days on which it must rain.
At a preliminary level, I get it. But, I'll probably need a few more questions of the type or a different explanation to understand this thoroughly. Thoughts anyone?

Wednesday, August 11, 2010

1 hr to go to office 20 kms away, 1 hr 15 mins to come back. On an avg, how much time do I waste everyday?

Finished Distance, Speed & Time from a GMATClub post. The tabular representation method is brilliant. It saved me a lot of time, since I don't have to keep writing the different forms of the formula S=D/T for every component of the question. Am definitely using the table form from now on! :-)

Also went through the post on Work problems. Didn't require much effort since my concepts are pretty clear. The only issue I have here is the time I take to solve a question, if I only rely on my concept. I will need to practice a lot of Work problems, and probably revisit my TIME notes for shortcuts. Buit I will get back to this post my diagnostic test, as the diagnostic test is untimed. Plus, there is only a limit to how much I can do in every topic over the next 2 days. Yup, probably giving the test on Saturday. Should revise everything on Friday. Phew...

Update on P&C: went through most of the solved examples in RS Aggarwal, need to wrap up Combinations with the last few questions from the book. Once this is done, need to go back to the GMATClub Math book chapter on Probability and try solving those examples I was having trouble with.

As for Remainders, still need to speak to that friend regarding the questions from the link I did not understand.

Tuesday, August 10, 2010

I had totally forgotten this! My Math tutor had taught us this in school. Thank you BTG for reminding me! :-) Very useful shortcut!!! You will NOT regret going through this video.

The Remainder of the previous post.

Before I forget, I also went through a post on Remainders. The formulae are easy, but when I tried solving the last question, I couldn't understand the reasoning. Also, there was a link to other questions - I had a problem grasping the reasoning there too. Need to sit down with my friend and understand all these concepts, before I can consider remainder theory finished.

The probability of my reading the new Artemis Fowl novel on the weekend is...

Went through Combinatorics and Probability chapters in GMATClub's Math Book. Combi was easy, but probability - there were some methods of solving examples that I couldn't grasp. I've done these topics in school, and I had a brilliant Math tutor who gave me pretty much all the tools required to solve questions of this type.

Am going to go through RS Aggarwal's Class XI book to revise my old way of solving these questions. Hopefully, I'll be able to solve the challenging examples from GMATClub's Math book after that.

Btw, am "working from home" today. Project is more or less done, have to put in around an hour's worth of my time on wrapping it up today. So thought it was best to stick around the house and wrap up Probability during the day...

I actually want to finish up and revise my theory by Friday evening or max Saturday, give the OG Diagnostic Test, and get to reading Atlantis Complex - the new Artemis Fowl novel! I did NOT buy it when I saw it in the book shop on Saturday, because I knew I'd want to read but I need to study now to make up for my loss of 3 weeks. Damn work!

Sunday, August 8, 2010

What's your excuse? (Number Theory & Percents)

Project is almost done. Have not been able to study properly for 3 weeks I think. But I'll just put in extra effort this week and wrap it up...I hope I'll be able to!

Done with:
1. Number Theory
2. Percents
from GMATClub's Math Book.

Phew.

Also, revised Mutliplying with 2 Reference Nos. Had forgotten how to do it. Need to revise Addition Chapter.
I must repeat myself - I LOVE Bill Handley's book! :-)

Sunday, July 25, 2010

Numbers

Did some questions from the Geometry chapter of a Career Launcher book. Learnt the alternate segment theorem which was not mentioned in GMATClub's Math Book - Geometry chapter.

Have begun Number Theory today.

Oh, and also, was on a crazy project putting in long hours so was unable to study. Dance class has moved to Monday & Thursday now, and should be back home by 8 max on these days, so waking up early is no longer a worry and my weekends are completely free to study. :-) It's looking good guys!

Tuesday, July 13, 2010

Sequences & Series

Finished AP GP from GMATClub's Math Book. Since we've done AP GP quite extensively in school, concepts are pretty clear to me. It's mostly just formulae otherwise.
Putting this in here because it won't be found everywhere:

(1) The mean and the medium of any arithmetic sequence is equal to the average of the first and last terms.
(2) The sum of an arthritic sequence is equal to the mean (average) times the number of terms.
(3) The product of n consecutive integers is always divisible by n! So, 4x5x6 (4*5*6=120) is divisible by 3!
(4) If you have an odd number of terms in consecutive set, the sum of those numbers is divisible by the number of terms.
(5) (4) above does not hold true for consecutive sets with an even amount of terms."

Monday, July 12, 2010

Everyone preparing for an entrance exam which has a quant section should seriously consider buying Bill Handley's Speed Mathematics. It makes all this Vedic Math crap that CAT institutes and books try to teach so bloody simple. He's written it so well, it's easy to understand, the chapters build on each other, it's just plain fantastic.

Anyway, now that my review for the book is over...

Did Chapters 8 & 9 (Multiplying using 2 reference nos. and addition). Feelling more and more like a math whiz these days. :-)

Sunday, July 11, 2010

Deviating from my standards

Sunday morning up with a lark,
I think I'll take a walk in the park...
Hey, hey, hey it's a beautiful day...
So, Sunday morning. And I've been up since 5. Spent about 90 minutes going through and understanding the concept of Standard Deviation. I've read it's not a common topic on the GMAT, but an 800-scorer can't afford to ignore any topic. ;-)

Went through Kaplan book's section on Averages (as suggested by 60-day Study Guide - BTG). Worked through it's practice set, which is quite simple. Moved on to Standard Deviation chapter from GMATClub's Math book. Very short. The author has posted a link to some PS and DS questions on SD which made me very happy. Till I realised they were questions from GMATPrep. At which point I quickly stopped. I want to have minimum repeat questions on my practice exams.

Did some random SD questions from GMATClub then, from non-official sources I hope.

Oh, and if you're wondering about the topic of this post - waking up at 5 for 2 straight weeks, and even on a Sunday is 3 standard deviations away from my mean! :-) (if you study the concept, you'll get it.)

Saturday, July 10, 2010

And it's a wrap.

Done with Geometry Theory. Got 38/42 correct in Kaplan book's practice sets. 3 questions - very silly mistakes. 1 question - although easy, it had a particular method to solve it. It's definitely a CP. Will post it soon.

Now starting off with Standard Deviation.

Thursday, July 8, 2010

How To Wrap Up The Geometry Theory Module Perfectly

Geometry theory from OG - check.
Geometry theory from GMATClub's Math book - check.
Go through FCs to drill the formulae into your brain - partially done.
Geometry theory from Kaplan - pending.
Action Plan (from BTG's 60-Day Study Guide: Day 15)
To Do:
• In Kaplan's GMAT 2010-2011 Premier with CD-ROM:
• Read the section on Lines and Angles (p. 293-295)
• Answer questions 1, 3 and 4 on the Lines and Angles Practice Set (p. 296-297)
• Read the section on Triangles (p. 299-404)
• Complete the Triangles Practice Set (p. 305-306)
• Read the section on Polygons (p. 306-308)
• Complete the Quadrilaterals and Other Polygons Practice Set (p. 308-311)
• Read the section on Circles (p. 311-314)
• Complete the Circles Practice Set (p. 315-317)
• Read the section on Multiple Figures (p. 317-319)
• Complete the Multiple Figures Practice Set (p. 319-321)
• Read the section on Solids (p. 321-324)
• Complete the Solids Practice Set (p. 324-326)
Note: I have the 2009-10 edition, so page numbers might be different.
I have 2 days to finish this. I will go through the theory section to see if I've missed out anything. If yes, I will make a FC for it. Then I will do the practice sets. :-)

Wednesday, July 7, 2010

A Love Triangle

Finished Triangles yesterday. :-)
Which translates into, Geometry theory is complete!
This morning, I stared going through my Geo FCs. Want to make sure all the concepts and formulae are drilled into my head. Will practice some geo questions after that, cos it's always fun to be able to answer questions once you know your theory!!!
Yey! Very happy today!!! :-)

Saturday, July 3, 2010

My Coordinates are 28° 35' N 77° 12' E

Coordinate Geometry from GMATClub's Math Book is finito! :-)

Polygons

Finished the chapter on Polygons from the GMAT Math Book at GmatClub. :-)

Tuesday, June 29, 2010

Fundamentally sound

Hi!
Plan for next 1 month: Go through GMAT Math book and other math resources (from GMAT Club forum) to form a complete understanding of concepts and formulae required for GMAT. Make FCs for formulae/concepts I don't already know.
31st July: Take diagnostic test (Math & Verbal) from OG11.
27th June - Circles
28th June - part of polygons

Tuesday, June 15, 2010

CP #10

GMAT Blue Quiz - Kaplan
UNDERSTAND EXPLANATION!!!
Question
Is a – b > 0?
(1)    a > 2b
(2)    b > a + 3
Solution
The inequality in the question stem can be manipulated so that the question reads "is a > b?"

At first glance, Statement (1) would seem to be sufficient. If a and b are both positive, and then a is certainly greater than b. But what if a and b are negative? If a = -3 and b = -2? Since -3 > -4, a would be greater than 2b; but since -2 > -3, b would be greater than a. Since Statement (1) can lead to either a yes or no answer, it is insufficient.

Manipulating the inequality in Statement (2) is more fruitful. Subtracting b and 3 from both sides gives you -3 > a-b. If that's true, then a – b is certainly less than zero. Statement (2) leads to a single, definite answer (which happens to be "no") and so is sufficient.

Kaplan Permier: Blue Quiz

Completed Kaplan Premier's Blue Quiz today. Scored an 87% overall. Got 26/30 right. Wrong - 2 CR (DOUBT IN #20 - ASK A KAPLAN INSTRUCTOR), 1 SC (idiom - as many...as) and 1 DS (ASK FRIEND!).

Monday, June 14, 2010

Speed Math: Multiplying Decimals

Went through the chapter on Multiplying Decimals. The concept is the same as any other multiplication, but one use of it is super-cool.
If you need to multiply 8 x 88, make it 8.0 x 88. Essentially, you're multiplying 80 x 88 and can just add a decimal point at the end of your answer. Super-awesome!
To Do
Hopefully will get to go through the next chapter (Multiplying Using Two Reference Numbers) today itself.
Tables upto 20!

Friday, June 11, 2010

Kaplan Diagnostic Quiz & Speed Math

Hi...
Work has kept me quite busy, so had left GMAT studies for sometime. It's time now.
Recap
Took the GMAT Diagnositc Quiz on Kaplan Premier's online companion. Scored 89% - 34 / 38 were correct answers. Got 1 wrong each in DS, PS, RC and CR. It was untimed.
To Do
While reviewing, there is 1 DS question I could not understand - will ask a friend - also, need to put it as a CP.
Another DS question took too long - must review that.
RC Strategy
In RC, writing what the para is talking about as short notes helps me. It's a PR method, but it seems to be working. It doesn't work in those passages where I have literally been unable to comprehend the meaning. To reduce the probability of that happening, I need to start taking out time to read (I used to be a voracious reader till time constrains brought my reading time down to near negligible). I also need to work on my vocab - I have Word Power Made Easy (WPME) by Norman Lewis. Maybe I should revisit it.
Speed Math
Have also been learning calculation shortcuts from Bill Handley's Speed Mathematics. It's actually quite fun and I've done a few chapters.
To Do
Do the chapter on decimal multiplication. Practise calculations.

Question

Two positive numbers differ by 12 and their reciprocals differ by 4/5. What is their product?

(A) 2/15
(B) 48/5
(C) 15
(D) 42
(E) 60

Solution

Don't be afraid to assign variables even when none are given in the problem. "Two positive numbers differ by 12" can be written as:
xy = 12
And "their reciprocals differ by 4/5" can be written as:
1/y – 1/x = 4/5
(Note: Here, we've assigned x as the bigger of the two numbers and y as the smaller, so we've intuited that 1/y is the larger reciprocal and 1/x the smaller, and so arranged them in that order to write 1/y – 1/x = 4/5).
Now we have a system of two variables and two equations. Note that it is NOT necessary to solve for x and y, since we are being asked for the product, xy.
First, let's simplify the second equation by finding a common denominator for the terms on the left:
x/(xy) – y/(xy) = 4/5
(xy)/(xy) = 4/5
Note that the denominator is xy, which is exactly the quantity we want to find.
Since we know from the first equation that xy = 12, substitute 12:
12/(xy) = 4/5
60 = 4xy
15 = xy
The correct answer is (C) 15.
-------------------------------------------
It was a very simple question. I've highlighted where I made mistakes. Both were such stupid errors. Even if I hadn't figured the 2nd one, I would've solved it by an extremely long method.

Monday, February 1, 2010

Day 31...finally

Today is Day 31. Yes, today. Sorry, been busy with the new job. Still got lots of learning to do, but I've put together a plan for GMAT again. I hope I'll follow it this time.

Day 31:
Went through mainly Geo related self-made FCs.

Yes, that's it. But it's a start. Specially amidst such a chaotic work schedule.