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03 May 2017, 04:43
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A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
5%
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Question Stats:
90% (01:01) correct
10%
(02:01)
wrong
based on 89
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Is the average (arithmetic mean) of a, b, and c greater than 12?
(1) The average (arithmetic mean) of a + 2, b − 7, and c + 6 is 10.
(2) a, b, and c are integers.
(1) The average (arithmetic mean) of a + 2, b − 7, and c + 6 is 10.
(2) a, b, and c are integers.
03 May 2017, 05:44
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the question asks for (a + b + c)/3 > 12 ???
implies a + b + c >36
stat 1: (a+2 + b-7 + c+ 6) = 30
a+b+c = 29,,suff
stat 2 : no useful info.,,
ans A
implies a + b + c >36
stat 1: (a+2 + b-7 + c+ 6) = 30
a+b+c = 29,,suff
stat 2 : no useful info.,,
ans A
03 May 2017, 06:11
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Bunuel
Is the average (arithmetic mean) of a, b, and c greater than 12?
(1) The average (arithmetic mean) of a + 2, b − 7, and c + 6 is 10.
(2) a, b, and c are integers.
(1) The average (arithmetic mean) of a + 2, b − 7, and c + 6 is 10.
(2) a, b, and c are integers.
Target question: Is the average (arithmetic mean) of a, b, and c greater than 12?
Statement 1: The average (arithmetic mean) of a + 2, b − 7, and c + 6 is 10
In other words, [(a + 2) + (b − 7) + (c + 6)]/3 = 10
Multiply both sides by 3 to get: (a + 2) + (b − 7) + (c + 6) = 30
Simplify to get: a + b + c = 29
The average of a, b and c = (a + b + c)/3 = 29/3
So, the average (arithmetic mean) of a, b, and c is NOT greater than 12
Since we can answer the target question with certainty, statement 1 is SUFFICIENT
Statement 2: a, b, and c are integers.
If it's not obvious that this information is not sufficient, consider the following two cases:
Case a: a = 100, b = 100 and c = 100, in which case the average of a, b and c IS greater than 12
Case b: a = 1, b = 1 and c = 1, in which case the average of a, b and c is NOT greater than 12
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT
Answer:
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