Of the numbers q, r, s, and t, which is greatest?

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by Brent@GMATPrepNow » Thu Dec 19, 2019 6:31 am
BTGmoderatorDC wrote:Of the numbers q, r, s, and t, which is greatest?

(1) The average (arithmetic mean) of q and r is s.
(2) The sum of q and r is t.
Target question: Of the numbers q, r, s, and t, which is greatest?

Statement 1: The average (arithmetic mean) of q and r is s
No information is given about t
Statement 1 is NOT SUFFICIENT

Statement 2: The sum of q and r is t.
No information is given about s
Statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined
Statement 1 tells us that (q + r)/2 = s
Multiply both sides by 2 to get: q + r = 2s

Statement 2 tells us that q + r = t

There are several values of q, r, s and t that satisfy BOTH statements. Here are two:
Case a: q = -1, r = 1, s = 0 and t = 0. In this case, the answer to the target question is r is the greatest value
Case b: q = 1, r = -1, s = 0 and t = 0. In this case, the answer to the target question is q is the greatest value
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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