For the problems on circular track and RTD, what are the basic concepts and variations possible? How important are these from the pt of view of the gmat? Got a question on circular tracks in MGMAT4 as below. Need more explanation and hints on how to solve these kind of problems 'quickly'.

Car B starts at point X and moves clockwise around a circular track at a constant rate of 2 mph. Ten hours later, Car A leaves from point X and travels counter-clockwise around the same circular track at a constant rate of 3 mph. If the radius of the track is 10 miles, for how many hours will Car B have been traveling when the cars have passed each other for the first time and put another 12 miles between them (measured around the curve of the track)?

4pi– 1.6
4pi+ 8.4
4pi+ 10.4
2pi– 1.6
2pi– 0.8

Also, 2 more questions:
1. What degree of understanding of clocks - time of meeting, angle between hands etc is necessary for gmat?

2. I am able to solve most of the quant questions on my own post the test but during the test, I just don't. Have found that I am not quick enough and have to guess on over 12 ques to complete the test on time.

For example, on an inequalities q, so many permutations to try or in a word problem, its long and complex. What can I do to build speed without compromising my accuracy? Taken 4 tests; started with 690 -> 700 -> 720 -> 700. Its not moving above 720 with quant at 70 to 74%ile.

Hope you can help.
Thanks
Subhashini

Circular tracks are no different from other RTD questions aside from the repetitive nature of the course. So all the typical RTD question variations could show up on questions about circular tracks as well, and the techniques you use on ordinary RTD questions will work on circular track questions as well..

Angle between hands questions are probably not going to become an issue on the GMAT, and to the extent that they do you’re probably okay as long as you remember that the hour hand will take one hour to go between two numbers, the minute hand takes an hour to go a full 360 degrees, and there are 12 numbers on the clock. Everything else is derivable from there..

The answer to your second question is practice and THOROUGH review. You need to ask yourself why you weren’t able to solve a question on the test but you could later. Ask yourself what type of problem it was and how you could have recognized what strategy to use. Ask yourself where things went wrong. If you can answer these questions, you’ll be well on your way to figuring out why you’re having this trouble and being able to fix it..

_________________
Tim Sanders
Manhattan GMAT Instructor