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Is x > 16?

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Source: — Data Sufficiency |

Re: Is x > 16?

by Brent@GMATPrepNow » Mon Jul 27, 2020 6:08 am
BTGModeratorVI wrote:
Thu Jul 23, 2020 6:36 am
Is x > 16?

1) x/4 > 4
2) 4/x < 1/4


Answer: A
Source: Math Revolution
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 > 16
Case b: x = -1, in which case x < 16
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer = A
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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