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What is the average (arithmetic mean) of j and k

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Source: — Data Sufficiency |

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by Brent@GMATPrepNow » Sun Oct 01, 2017 2:17 pm
lheiannie07 wrote:What is the average (arithmetic mean) of j and k ?

(1) The average (arithmetic mean) of j + 2 and k + 4 is 11.
(2) The average (arithmetic mean) of j, k, and 14 is 10.
Target question: What is the average (arithmetic mean) of j and k ?

Statement 1: The average (arithmetic mean) of j + 2 and k + 4 is 11.
In other words, [(j+2) + (k+4)]/2 = 11
Multiply both sides of the equation by 2 to get: (j+2) + (k+4) =22
Simplify: j + k + 6 = 22
So, j + k = 16
Average of j and k = (j + k)/2 = 16/2 = 8
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: The average (arithmetic mean) of j, k, and 14 is 10.
In other words, (j + k + 14)/3 = 10
Multiply both sides of the equation by 3 to get: j + k + 14 = 30
So, j + k = 16
Average of j and k = (j + k)/2 = 16/2 = 8
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: D

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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