MGMAT CAT#1:Exponents/Algebra

[afvatcha]

Hi, I came across this data suff. in the MGMAT CAT#1.

8a(1/4)b = ?

(1) b = 1.5a
(2) a = 2

The correct answer is (A).

I understand why (A) is sufficient, but why isn't (B). The explanation says 3a-2b. So we can plug in A and set 3a-2b to 0. Well why can't you do that for (B)?

[Ben Ku]

Please be clear when re-typing the problem. This problem is actually:

(8^a)*(1/4)^b = ?

To do this problem, we can simplify this expression so everything has the same base.

(2^3)^a * (2^-2)^b
= 2^3a * 2^-2b
= 2^(3a - 2b)

The question is REALLY asking for "What is 3a - 2b?".

Statement (1) is sufficient, because if b = 1.5a, then 3a - 2b = 3a - 2(1.5a) = 3a - 3a = 0.

Hope that helps.