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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In 2007, the arithmetic mean of the annual incomes of Jack
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We can let the incomes of Jack, Jill, and Jess = a, b, and c, respectively, and create the equations: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
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
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