Question

The mean of seven numbers is 12.0. When one new number is added , the average of eight numbers becomes 12.5 . What is the new number?

Answer 1

(12 * 7 + n)8=12.5
(12 * 7 + n)= 100
N= 16. The new number will be 16. Hope this helps. :)

Answer 2

I agree that the answer is 16. Just plugging the number into a equation equaled to 100