Final Stretch

Hey...so I'll fill you in real quick. I gave an MGMAT test on Sunday morning and scored a crappy 670 (Q45 V36). Felt really crummy post that, obviously. And then I fell sick on Monday, and have had fever since. I've tried studying a little from OG. Finished reviewing my Math FCs today. Now I need to buckle up and really revise my SC notes from MGMAT's guide, and probably practice a few questions from OG to reinforce those rules. Other than that, today's the first day I've not had fever. So I guess I'm getting better. Feeling a little tired though - I guess it's just a little weakness.
I know I wanted to do a whole lot more of fine-tuning before my actual exam, and obviously the falling test scores weren't helping my confidence either. But, you know what, I think I've put in a lot of effort over the past few weeks, and hopefully I shall be fully fit to give my exam on the 1st. I don't feel like giving up just yet. The only change in plan is that I will give my final practice test - GMATPrep #2 on Sunday instead - so that I can review/practice a little bit more before the test. I'm sure the practice test will go well, and I'll be on my way to scoring well on the GMAT.

Parting words for today...

"I promise myself...
To be so strong that nothing can disturb my peace of mind.
To think only of the best... and to expect only the best.
To be too large for worry, too strong for fear, and too happy to permit the presence of trouble.
To live in the faith that the whole world is on my side..."

13 days to go!

Hello! I went through incorrect questions on last 2 tests, and found 2 math topics to focus on: Number Properties (specially Divisibility & Primes), and Inequalities. Done going through all the Number Properties questions from OG11, 12 and OG Quant supplement. Might go through "Integer Properties" category of questions from my BTG account.
Going to do the same for Inequalities today.
Finished Modifiers from MGMAT SC. Need to go through my notes again, and practice some more questions from OGV for those topics.

Another practice test tomorrow morning.

Happy studying you guys!!!

Verbs Video help

Verb Tense help from Ron.
http://vimeo.com/17098165

CP #25

MGMAT CAT#2


The greatest common factor of 16 and the positive integer n is 4, and the greatest common factor of n and 45 is 3. Which of the following could be the greatest common factor of n and 210?

		3
		14
		30
		42
		70

Solution

The greatest common factor (GCF) of two integers is the largest integer that divides both of them evenly (i.e. leaving no remainder).

One way to approach the problem is to consider what the GCFs stated in the question stem tell us about n:

The greatest common factor of n and 16 is 4. In other words, n and 16 both are evenly divisible by 4 (i.e., they have the prime factors 2 × 2), but have absolutely no other factors in common. Since 16 = 2 × 2 × 2 × 2, n must have exactly two prime factors of 2--no more, no less.

The greatest common factor of n and 45 is 3. In other words, n and 45 both are evenly divisible by 3, but have absolutely no other factors in common. Since 45 = 3 × 3 × 5, n must have exactly one prime factor of 3--no more, no less.  Also, n cannot have 5 as a prime factor.

So, n must include the prime factors 2, 2, and 3. Furthermore, n is not divisible by 8, 9, or 5.

The number 210 has the following prime factorization: 210 = 2 x 3 x 5 x 7. Thus n and 210 are both divisible by 2 and 3, and both might be divisible by 7, but it is not the case that both numbers are divisible by 4 or by 5:

(A) 3: missing a 2
(B) 14: missing a 3
(C) 30: n cannot be divisible by 5
(D) 42: Correct. n and 210 are both divisible by 2 and 3, and n could be divisible by 7.
(E) 70: n cannot be divisible by 5 and must be divisible by 3.

The correct answer is D.

CP #24

MGMAT CAT#2

Is the positive integer N a perfect square?

(1) The number of distinct factors of N is even.
(2) The sum of all distinct factors of N is even.

Answer Explanation:
(1) SUFFICIENT: The factors of any number N can be sorted into pairs that multiply to give N. (For instance, the factors of 24 can be paired as follows: 1 and 24; 2 and 12; 3 and 8; 4 and 6.) However, if N is a perfect square, one of these ‘pairs’ will consist of just one number: the square root of N. (For example, if N were 49, it would ahve the factor pair 7 × 7) Since all of the other factors can be paired off, it follows that if N is a perfect square, then N has an odd number of factors. (If N is not a perfect square, then all of its factors can be paired off, so it will have an even number of factors.) This statement then implies that N is not a perfect square.

(2) SUFFICIENT: Let N be a perfect square. If N is odd, then all factors of N are odd. Therefore, by the above reasoning, N has an odd number of odd factors, so their sum must be odd. If N is even, let M be the product of all the odd prime factors (as many times as they appear in N – not distinct) of N, which is also a perfect square. (For instance, if N = 100, then M =5 × 5 = 25.) Then the sum of factors of M is odd, by the above reasoning. Furthermore, all other factors of N (i.e., that don’t also divide M) are even. The sum total is thus odd + even = odd.
Therefore, the sum of the factors of any perfect square is odd, so this statement implies that N is not a perfect square.
This statement can also be investigated by trying several cases of even perfect squares (4, 16, 36, 64, 100), noting that in each case the sums of the factors are odd, and generalizing.

The correct answer is D.

-----------

I picked numbers to get to my answer, but made a silly mistake by omitting "1" as a distinct factor in Statement II.

And to the MGMAT explanation - hunh?!

Yes, of course I know what a verb is! Oh, ummm...who's Command Subjunctive?

The Verb got Tensed, I couldn't gauge its Mood correctly, and now I'm hearing Voices in my head asking me if the impact of the verb has continued into the present day, and if the hypothetical statement about the future is conditional or not.

Yup, that's what I thought I was reading while going through MGAMT SC Guide Chapter - Verb Tense, Mood & Voice - today. Although it took a lot of time to get through, I was patient with it. I made notes, pretty notes :)
But the most useful part was going through the Problem Set & OG12 questions and understanding why I got an answer correct or incorrect. That's when all the "theory" from the chapter started to sink in, and yes, even make sense! :)

No, I didn't touch anything else today, but this was good. I'm feeling a lot more confident.
And after yesterday's, ummm..."meltdown"(?) :p, I thought through it and realised that I just have to give it my best shot. And the Universe will take care of the rest of it. I should just continue doing what I need to do.

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.

The correct answer is A.


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.

The correct answer is E. 

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.

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*

Manhattan GMAT SC Guide : You're going down.

:-)

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

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!

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.

Ok, no...I'm back!

Remember the last post? Scratch that. There will never be a "right time" to study for GMAT. This IS the right time. Just going to buy MGMAT's SC guide. I have 4 days to go through it once, since work starts 4th Jan. :-) Yey! I'm so glad to be hitting my books again! :-)

Manhattan GMAT Sentence Correction Guide 4th ed in New Delhi

I have been frantically looking for this as I have lots of free time in the coming week. I called up Om Book Shop and guess what? They have it! I still don't have it in my hands, so I cannot confirm. Will confirm by tonight. Omg. I really hope they actually have it!!! Edit: They DO have it. :-)

And since my GMAT date is getting closer, I think the following post has done me some good. Def starting OG12 this week.
http://gmatclub.com/forum/760-in-5-weeks-you-can-do-it-87741.html

A link to links & a big fat THANK YOU!

I've been updating my Important Links post periodically, and I didn't mention the changes because I assumed that if anyone wanted to know what was new, they'd just go to the post and find out (I change the font of new stuff to bold & italic so that it's easier to spot). However, I must make a special mention of my Important Links post today, mainly because I believe the two new links I've added might be truly awesome, so awesome that they should have an additional post about them.
1. GMATClub has launched a new GMAT Math Book Open Project, which I think is a fantastic idea. Currently, you can find DETAILED chapters on Triangles, Polygons, Probability & Combinatorics. Other topics in the book are links to Sequences & Series, Word Problems, etc. OMG!!! :-)
Edit: I've just begun going through the Triangles chapter in this, and it's unbelievable! Don't need to try looking for any another source of Math theory!!! Seriously.
2. GMATClub has also added the Question of the Day feature!
Wow, I think they should probably pay me for "advertising" this! Haha...Anyway, what I really like about sites like GMATClub is that they seem to truly want to help out students, the part about all these great *free* features being the key! That's why I like BeatTheGmat too. Just the number of helpful GMAT & MBA related articles they post daily!!! And then there's MGMAT. Although most of their stuff is paid (they're basically paid classroom tutors!), they don't behave like maniacs trying to put a price on every single piece of advice, question, or solution they provide. Go check out their forums and MBA Resources pages if you don't believe me.
I guess a big fat THANK YOU is in order for these sites and the people who contribute to them!!! :-)

PS. I should atleast get paid for the amount of effort it took to provide relevant links in this post! ;-)

CP #3

Another good question. They haven't posted the answer yet.

MGMAT Challenge Problem of the Week

10/26/09

Machines A, B, and C

Machines A, B, and C can either load nails into a bin or unload nails from that bin. Each machine works at a constant rate that is the same for loading and for unloading, although the individual machines may have different rates. Working together to load at their respective constant rates, machines A and B can load the bin in 6 minutes. Likewise, working together to load at their respective constant rates, machines B and C can load the bin in 9 minutes. How long will it take machine A to load the bin if machine C is simultaneously unloading the bin?

(A)	12 minutes
(B)	15 minutes
(C)	18 minutes
(D)	36 minutes
(E)	54 minutes

I think the answer is C. I don't think my method is long, but I do think I took a little extra time to think up of the process (again, cos I doubted my concept clarity a little, and so didn't quickly start to solve it the way I was thinking...tried applying formula first, but what good is that if I don't know the concept extremely well?). I'll wait till tomm for them to give the right answer, as well as their explanation. Then I'll compare my answer with theirs. 

Edit: The OA is C.

CP #2

Wicked question by MGMAT this week! Check it out...


MGMAT Challenge Problem of the Week

10/19/09

Question

If a, b, and c are positive integers, with a < b < c, are a, b, and c consecutive integers?

(1) 1/a – 1/b = 1/c

(2) a + c = b² – 1

(A)	Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
(B)	Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
(C)	BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
(D)	EACH statement ALONE is sufficient.
(E)	Statements (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data are needed.

Answer

The question can be rephrased "Is b = a + 1 and is c = a + 2?"

One way to approach the statements is to substitute these expressions involving a and solve for a. Since this could involve a lot of algebra at the start, we can just substitute a + 1 for b and test whether c = a + 2, given that both are integers.

Statement 1: SUFFICIENT.
Following the latter method, we have
1/a – 1/(a + 1) = 1/c
(a + 1)/[a(a + 1)] – a/[a(a + 1)] = 1/c
1//[a(a + 1)] = 1/c
a² + a = c

Now we substitute a + 2 for c and examine the results:
a² + a = a + 2
a² = 2
a is the square root of 2. However, since a is supposed to be an integer, we know that our assumptions were false, and a, b, and c cannot be consecutive integers.

We can now answer the question with a definitive "No," making this statement sufficient.

We could also test numbers. Making a and b consecutive positive integers, we can solve the original equation (1/a – 1/b = 1/c). The first 4 possibilities are as follows:
1/1 – 1/2 = 1/2
1/2 – 1/3 = 1/6
1/3 – 1/4 = 1/12
1/4 – 1/5 = 1/20

Examining the denominators, we can see that c = ab. None of these triples so far are consecutive, and as a and b get larger, c will become more and more distant, leading us to conclude that a, b, and c are not consecutive.

Statement 2: SUFFICIENT
Let's try substituting (a + 1) for b and (a + 2) for c.

a + a + 2 = (a + 1)² – 1
2a + 2 = a² + 2a
2 = a²

Again, we get that a must be the square root of 2. However, we know that a is an integer, so the assumptions must be false. We can answer the question with a definitive "No," and so the statement is sufficient.

The answer is D: Each statement is sufficient.
--------------------------------------------------------------
The first option required just a little more calculation that the second.
I did get the answer on my first try, but I still wanted to post it here because the logic that struck me while trying to solve it may not have struck me at another point of time. I know I've opened my mind to newer ways of solving questions. Earlier, even if the idea would've struck me, just knowing it was a little bit more complicated than what I'm extremely comfortable with, I would've confused myself. Now, I take a deep breath, try to understand why I'm thinking that way, and the answer comes. Even if it doesn't, atleast I'm aware of the logic I used! I should be thanking the people at T.I.M.E classes for this. The Math teacher in Delhi (Kailash Colony) as well as Bombay (Charni Road) were pretty damn good. And they have helped me think of Math in a simpler, clearer manner, and I think I'm getting over my fear now, and beginning to not underestimate myself.
I think I've left my notepad at home. I should write my thought process here.

Challenge Problem (CP) #1

From now on, I'll post the problems I find on the net that I find challenging, didn't get in the first try or didn't solve by the better method. Here's the first one!

NOTE: Whenever the problem is from MGMAT's CP of the Week, click on the link to go the original source of the problem.

MGMAT Challenge Problem of the Week


10/05/09

Question

Xander, Yolanda, and Zelda each have at least one hat. Zelda has more hats than Yolanda, who has more than Xander. Together, the total number of hats the three people have is 12. How many hats does Yolanda have?

(1) Zelda has no more than 5 hats more than Xander.

(2) The product of the numbers of hats that Xander, Yolanda, and Zelda have is less than 36.

Answer

Write x for the number of hats Xander has, y for the number of hats Yolanda has, and z for the number of hats Zelda has. From the question stem, we know that x < y < z and that x + y + z = 12. Moreover, since each person has at least one hat, and people can only have integer numbers of hats, we know that x, y, and z are all positive integers. With this number of constraints, we should go ahead and list scenarios that fit all the constraints. Start with x and y as low as possible, then adjust from there, keeping the order, keeping the sum at 12, and ensuring that no two integers are the same.

Scenario	x	y	z
(a)	1	2	9
(b)	1	3	8
(c)	1	4	7
(d)	1	5	6
(e)	2	3	7
(f)	2	4	6
(g)	3	4	5

These are the only seven scenarios that work. As a reminder, we are looking for the value of y. Now, we turn to the statements.

Statement (1): INSUFFICIENT. We are told that z – x is less than or equal to 5. This rules out scenarios (a) through (c), but the last four scenarios still work. Thus, y could be 3, 4, or 5.

Statement (2): INSUFFICIENT. We are told that xyz is less than 36. We work out this product for the seven scenarios:
(a) 18
(b) 24
(c) 28
(d) 30
(e) 42
(f) 48
(g) 60

We can rule out scenarios (e) through (g), but (a) through (d) still work. Thus, y could be 2, 3, 4, or 5.

Statements (1) and (2) together: SUFFICIENT. Only scenario (d) survives the constraints of the two statements. Thus, we know that y is 5.

The correct answer is (C): BOTH statements TOGETHER are sufficient to answer the question, but neither statement alone is sufficient.

Update/Day 9

Sorry for not updating earlier!

Day 6: MGMAT FCs - Word Translations (WT)
Day 7: MGMAT FCs - EIVs
Day 8: Theory (only formulas) for P&C, Interest (SI & CI), Sequences (AP,GP)
Day 9 (TODAY, 13th Oct): Just gave a 40 minute Math Diagnostic on MGMAT site. Was good! But questions were of 200-500 level. I got 19/20 questions right. The 1 I got wrong was silly - was a remainders question, and I should've just used common sense instead of trying to fit in a formula. Anyway, yay!

If I'm not too tired in the evening, I'll try doing some more from IMS BRM material on P&C...let's see.
Btw, I'm going to pay for GMAT by myself! :-) (earlier, my parents were going to)
I will be done with it by Dec end, and then...I'm going to apply to BCG, Bain & Co, and other consultancy firms in that league. I want to work there!!! I *will* work there.
GMAT studying, as you can see, is going at a slow pace, but it's consistent atleast. I want to try giving the OG11 diagnostic by this weekend (3-day weekend coming up! Yay Diwali!)

I'm off to try exercising a little before I go to office.

Happy studying!