Question

The average of eight numbers is 56. When one of the numbers was left out, the mean decreased to 54. What number was left out?

Answer 1

Explanation:

Given the average of 8 numbers = 56.

Then the Total sum of 8 numbers = 56 * 8

= 448.

Sum of 1st three numbers = 49 + 57 + 72

= 178.

So, the total = 448 - 178

= 270.

Average of the other 5 numbers = 270/5

= 54.

Verification:

178 + 270 = 448/8

= 56.