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The average of N numbers is 21. If a number 57 is removed, then average becomes 17. What is the value of N?

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The average of N numbers is 21. If a number 57 is removed, then average becomes 17. What is the value of N?
1). 10
2). 8
3). 9
4). 11


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1 answers

2 vote
Answered by on | Votes 2 |

Average of N numbers = 21

The sum of N numbers = 21N

Now,

⇒ 21N - 57 = 17(N - 1)

⇒ 21N - 17N = 57 - 17

⇒ 4N = 40

⇒ N = 10

Hence, the value of N = 10

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