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What is the average of x and y?

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by yalanand » Sun Feb 01, 2009 12:18 am
The average of a set of 9 numbers is 25. When x and y are added to the set, the average of the set of 11 numbers is 21. What is the average of x and y?

(A) 3
(B) 9
(C) 11
(D) 21
(E) 23
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Re: What is the average of x and y?

by piyush_nitt » Sun Feb 01, 2009 12:40 am
yalanand wrote:The average of a set of 9 numbers is 25. When x and y are added to the set, the average of the set of 11 numbers is 21. What is the average of x and y?

(A) 3
(B) 9
(C) 11
(D) 21
(E) 23
Given

Average of 9 nos = 25

total of 9 nos = 25* 9 = 225 - (1)

Also, Average of 11 nos = 21

total of 11 nos = 21* 11 = 231 (2)

subtracting (2) -(1)

= 6 => total of 2 nos

therefore average of x and y is 3

IMO A
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