Target question: Does 8x = 16 + 2x ?NandishSS wrote:Does 8x = 16 + 2x ?
(1) -3x is greater than or equal to -9
(2) 2x is greater than or equal to 6
This is a good candidate for rephrasing the target question.
Aside: Here's a video with tips on rephrasing the target question: https://www.gmatprepnow.com/module/gmat- ... cy?id=1100
Take: 8x = 16 + 2x
Subtract 2x from both sides to get: 6x = 16
Divide both sides by 6 to get: x = 16/6 = 8/3 = 2 2/3
REPHRASED target question: Does x = 2 2/3?
Statement 1: -3x is greater than or equal to -9
In other words, -3x ≥ -9
Divide both sides by -3 to get: x ≤ 3 [we flipped the direction of the inequality since we divided both sides by a NEGATIVE value]
There are several values of x that satisfy the condition that x ≤ 3.
So, x COULD equal 2 2/3 or x MIGHT NOT equal 2 2/3
Since we cannot answer the REPHRASE target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: 2x is greater than or equal to 6
In other words, 2x ≥ 6
Divide both sides by 2 to get: x ≥ 3
If x is GREATER than or equal to 3, then x can NEVER equal 2 2/3
In other words, the answer to our REPHRASED target questions is NO, x does not equal 2 2/3
Since we can answer the REPHRASED target question with certainty, statement 2 is SUFFICIENT
Answer = B
Cheers,
Brent
