Question

The mean of a set of seven numbers is 81. If one of the numbers is discarded,the mean of the remaining numbers is 78. The value of discarded number is

Answer 1

Explanation:

(seven numbers total) / 7 = 81

seven numbers total = 7 * 81 = 567

NOW REMOVE ONE OF THE NUMBERS

( Sum of six numbers) / 6 = 78

sum of six numbers = 6 * 78 = 468

sum of seven numbers - sum of six numbers = the number removed

567 - 468 = 99 <===number removed