The average of four numbers is 20, and one of these four numbers is 26. What is the average of the remaining three numbers?

Correct option is A

Given:

Average of four numbers is 20

One the numbers is 26

Formula Used:

​$$Average = \frac{Sum\ of\ observations}{Number\ of \ observations}$$​​

Solution:

Total of four numbers = 20 $$\times$$​ 4 = 80

Sum of other three numbers = 80 - 26 = 54

Average =$$\frac{54}{3} =18$$​​

Alternative Method(Shortcut):

If the fourth numbers is removed then

The extra sum to be removed from average =26-20 = 6

Here extra sum to be divided into equal numbers of observations = $$\frac{6}{3} = 2$$​​

New average  = 20 - 2 = 18