soni_pallavi wrote:Q) If p is a positive is p > 4 ?
1) p^4 = 256
2) (p^2 - 1)(p - 4) > 0
Target question:
Is p > 4 ?
Statement 1: p^4 = 256
256 = (4)(4)(4)(4)
So, if p^4 = 256 (and p is positive), then we can be certain that p = 4
Once we know the value of p, we can answer the
target question with certainty, which means statement 1 is SUFFICIENT
Statement 2: (p^2 - 1)(p - 4) > 0
Factor to get: (p-1)(p+1)(p-4) > 0
There are several values of p that meet this condition. Here are two:
Case a: p = 1/2 in which case
p is not greater than 4
Case b: p = 5 in which case
p is greater than 4
Since we cannot answer the
target question with certainty, statement 2 is NOT SUFFICIENT
Aside: jkaustubh noted that p=0 satisfies the given inequality, but the question tells us that p is positive. As such, p cannot equal 0
Answer =
A
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
