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In 2007, the arithmetic mean of the annual incomes of Jack

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by AAPL » Thu Jun 28, 2018 7:00 am

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C

D

E

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In 2007, the arithmetic mean of the annual incomes of Jack and Jill was $3800. The arithmetic mean of the annual incomes of Jill and Jess was $4800, and the arithmetic mean of the annual incomes of Jess and Jack was $5800. What is the arithmetic mean of the incomes of the three?

A. $4000
B. $4200
C. $4400
D. $4800
E. $5000

The OA is D.

(Sal Jack + Sal Jill) / 2 = 3800
Sal Jack + Sal Jill = 7600

Same logic for other cases

S Jill + S Jess = 9600
S Jess + S Jill = 11600

Add all of them up

2 * S Jack + 2* S Jill + 2* Jess = 28800
(S Jack + S Jill + S Jess) = 28800 / 6 = 4800. Option D.

Has anyone another strategic approach to solve this PS question? Regards!
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Source: — Problem Solving |

by Jeff@TargetTestPrep » Mon Jul 02, 2018 8:51 am
AAPL wrote:In 2007, the arithmetic mean of the annual incomes of Jack and Jill was $3800. The arithmetic mean of the annual incomes of Jill and Jess was $4800, and the arithmetic mean of the annual incomes of Jess and Jack was $5800. What is the arithmetic mean of the incomes of the three?

A. $4000
B. $4200
C. $4400
D. $4800
E. $5000
We can let the incomes of Jack, Jill, and Jess = a, b, and c, respectively, and create the equations:

a + b = 7600

and

b + c = 9600

and

a + c = 11600

Adding these together:

2a + 2b + 2c = 28,800

a + b + c = 14,400

So the average of all 3 numbers is 14,400/3 = 4,800,

Answer: D

Jeffrey Miller
Head of GMAT Instruction
[email protected]

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