SOLUTION: The average set of n numbers is 23. When -35 is added to the set, the average is 21. How many numbers were in the original set?

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Question 1129606: The average set of n numbers is 23. When -35 is added to the set, the average is 21. How many numbers were in the original set?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The average set of n numbers is 23. When -35 is added to the set, the average is 21.
How many numbers were in the original set?
:
%2823n-35%29%2F%28n%2B1%29 = 21
23n - 35 = 21(n+1)
23n - 35 = 21n + 21
23n - 21n = 21 + 35
2n = 56
n = 56/2
n = 28
:
:
Check this
23(28) - 35 = 609
609/29 = 21