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!

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.

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.