Is w+h4w+h4 positive?

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Source: — Data Sufficiency |

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by [email protected] » Sun Jan 28, 2018 12:39 pm
Hi ardz24,

This question is built around some Number Property Rules, so you can either TEST VALUES or use those NP rules to get to the correct answer.

We're asked if (W + H^4) is positive. This is a YES/NO question.

Before we get to the two Facts, it's worth noting that H^4 can NEVER be negative (it can be 0 when H=0, but in all other situations, H^4 will be POSITIVE). Thus, this question really comes down to the value of W....

1) H is positive

Fact 1 tells us that H is POSITIVE, so H^4 will be POSITIVE. However, it does NOT tell us anything about the value of W.

IF... H=1, W=1, then (H+W^4) = 2 and the answer to the question is YES.
IF... H=1, W= -2, then (H+W^4) = -1 and the answer to the question is NO.
Fact 1 is INSUFFICIENT

2) W is positive

Since W is POSITIVE, and we know that H^4 is >= to 0, then we know that (W+H^4) MUST be POSITIVE and the answer to the question is ALWAYS YES.
Fact 2 is SUFFICIENT

Final Answer: B

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