Data Sufficiency

BTGModeratorVI wrote: ↑

Tue Feb 16, 2021 8:13 am

Is x^3 equal to 125 ?

(1) x > 4
(2) x < 6

Answer: E
Source: Princeton Review

Target question: Is x^3 equal to 125 ?

REPHRASED target question: Does x = 5?

When I scan the two statements, they both feel insufficient, AND I’m pretty sure I can identify some cases with conflicting answers to the target question. So, I’m going to head straight to……

Statements 1 and 2 combined
Statement 1 tells us that x > 4
Statement 2 tells us that x < 6
Combine to get: 4 < x < 6
Since we're not told x is an INTEGER, there are infinitely man y values of x that satisfy BOTH statements. Here are two:
Case a: x = 5. In this case, the answer to the REPHRASED target question is YES, x is equal to 5
Case b: x = 5.1. In this case, the answer to the REPHRASED target question is NO, x is not equal to 5
Since we can’t answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E

Cheers,
Brent