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List \(K\) consists of seven numbers. Is the average

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List \(K\) consists of seven numbers. Is the average

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GMAT Paper Tests

List \(K\) consists of seven numbers. Is the average (arithmetic mean) of the seven numbers negative?

1) Four of the seven numbers in list \(K\) are negative.
2) The sum of the seven numbers in list \(K\) is negative.

OA B

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AAPL wrote:
GMAT Paper Tests

List K consists of seven numbers. Is the average (arithmetic mean) of the seven numbers negative?

1) Four of the seven numbers in list K are negative.
2) The sum of the seven numbers in list K is negative.
Target question: Is the average (arithmetic mean) of the seven numbers negative?

Statement 1: Four of the seven numbers in list K are negative.
There are several scenarios that satisfy statement 1. Here are two:
Case a: List K = {-10, -10, -10, -10, 1, 1, 1}. Average = sum/7 = -37/7. The answer to the target question is YES, the average IS negative
Case b: List K = {-1, -1, -1, -1, 10, 10, 10}. Average = sum/7 = 26/7. The answer to the target question is NO, the average is NOT negative
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: The sum of the seven numbers in list K is NEGATIVE.
Average = (sum of all 7 numbers)/7
So, we get: Average = NEGATIVE/7 = some negative number
The answer to the target question is YES, the average IS negative
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: B

Cheers,
Brent

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