MathRevolution wrote:
Is x>16?
1) x/4 > 4
2) 4/x < 1/4
Target question: Is x > 16? Statement 1: x/4 > 4 Multiply both sides by POSITIVE 4 to get: x > 16
Perfect!!
Since we can answer the
target question with certainty, statement 1 is SUFFICIENT
Statement 2: 4/x < 1/4 Multiply both sides by POSITIVE 4 to get: 16/x < 1
NOTE: we must avoid the temptation to multiply both sides by x to get: 16 < x. Doing so would be incorrect since we don't know whether x is POSITIVE or NEGATIVE.
Aside: for more on this, see our free video here:
https://www.gmatprepnow.com/module/gmat ... /video/979 There are several values of x that satisfy statement the fact that 16/x < 1. Here are two:
Case a: x = 20, in which case
x > 16Case b: x = -1, in which case
x < 16Since we cannot answer the
target question with certainty, statement 2 is NOT SUFFICIENT
Answer = A
Cheers,
Brent
4/x < 1/4 .... I can flip the fraction and change '> 'sign so x/4>1/4...........hence x>16 ........(B) is sufficient.