DS question from GMAT PREP - III

jay2007 · Posted: Mon Oct 08, 2007 10:12 pm Post subject: DS question from GMAT PREP - III

Can somebody help me in solving this problem?

achandwa · Posted: Tue Oct 09, 2007 11:42 am Post subject:

Assume Bob made Y items last week. Thus he made:

36 * X + (Y-36) * 1.5X - assuming Y > 36, or
36 * X - if Y <= 36

i) Bob made $480 last week

Therefore, 36 * X + (Y-36) * 1.5X = 480 - since we do not know if Y <=36 we need to consider this general case.
2 variables and one equation - not sufficient to solve

ii) Bob made 2 more items this week than he did last week and he made $510. Thus he made Y+2 items this week and,

36 * X + (Y+2-36) * 1.5X = 510.
36 * X + (Y-34) * 1.5X = 510
Again 2 variables and one equation - not sufficient to solve

But combining i) and ii), we have 2 variables and 2 unknowns. That's enough info to solve the problem. Hence C.

santsark · Posted: Tue Oct 09, 2007 11:18 pm Post subject:

achandwa - you are making an assumption that Y>36.

If this assumption is not true, then won't the answer be different.

I think it should be E.

achandwa · Posted: Wed Oct 10, 2007 4:33 am Post subject:

On second thought, I think you are right. Thanks for pointing it out.

jay2007 · Posted: Wed Oct 10, 2007 7:44 pm Post subject:

santsark is right. I also assumed that y > 36 and choose C, which is not the right answer.

OA is E.