Is a

Question

Is a < b?

(1)  a^b < b^a

(2)  \frac{a}{b} > 1

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TestPrepUnlimited · Answer

Statement 1:
We know nothing on a or b yet, we cannot simplify this to a < b so cannot prove a < b. Some examples we can use here:
\(2^3 < 3^2\) => \(a < b\) . Yes.
\(5^2 < 2^5\) => \(a > b\). No.

Statement 2:
This tells us a and b have the same sign. However, we cannot simplify this expression. Insufficient.

Combined:
Positive a and b give a > b from (2). Negative a and b give a < b from (2). We just need to find a case for each scenario that satisfies (1) to say insufficient.
For the positive case, we can recycle \(5^2 < 2^5\). For the negative case, we can let \(b\) be a negative odd number and \(a\) be a negative even number.
\((-4)^{-3} < (-3)^{-4}\) for example will satisfy (1) and also give us a < b. Therefore combined it is still insufficient.

Ans: E

Bunuel

Is a < b?

(1) \(a^b < b^a\)

(2) \(\frac{a}{b} > 1\)

Are You Up For the Challenge: 700 Level Questions

Sejal16 · Answer

Option B tells us that a>b as a/b >1, hence answer should be b.
Please explain.

globaldesi · Answer

for your question consider
a = -6 and b = -3
then a/b >1 but a is actually less than b
whereas
a = 6 and b =3
here a is greater than b 
hence insufficient
Hope it helps

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Is a < b? (1) a^b < b^a (2) a/b > 1

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