bblast wrote:Is it sensible that while plugging in answer choices(especially in problems obvious with such traps) and back solving in a GMAT PS we should start with option C and then goto E and then A,B ?

Generally speaking, starting with answer choice C is preferable. If you can determine which direction you need to go (high or low), you can eliminate 2 more answer choices right then and there.

Having said that, I do include several important caveats:

1) Don't sweat trying to determine the direction. If it's not immediately apparent, just pick a direction and go - it doesn't make sense to spend precious time trying to reason through a difficult puzzle. Plug in another answer, and see if the result brings you closer to where you need to go or further away, and act accordingly.

2) An overarching rule is "plug in the easy answers first". Sure, the method says "start with C", but If C happens to be 7.9 and D is 8, you start with the nice integer, and bugger the method. (unless 7.9 presents some significance for the question, of course). Reverse PI should make your life easier, not more difficult. More importantly, it's supposed to be the safer choice for some questions, and working with uncomfortable numbers is not safe. See my featured for an example of a GMATPREP question where blindly starting with C doesn't make sense.

https://www.beatthegmat.com/mba/2011/04/ ... iters-mind

I recommend starting with B or D. Since answers are arranged from low to high, if you check B you have a 40% chance of getting the answer right on the first try. (20% if B is correct, and 20% for A if B is too big.)Then going to D you will definitely find the answer depending on whether D is correct, too low, or too high. You never need to check more than two answers.