Question

The average of 6 numbers is 8.5.when one number is discarded the average of the remaining number becomes 7.2.what is the discarded number

Answer 1

Average of 6 no = 8•5
therefore sum of 6 numbers =
8•5 * 6 = 51

If one no is discarded then the average of remaining no or average of 5 numbers = 7•2
therefore sum of 5 numbers =
7•2 * 5 = 36

now, the discarded no =
(sum of 6 no) - (sum of 5 numbers)
51 - 36 = 15
So answer : discarded no is 15

Hope it helps you !!!