The average of 7 numbers is 43. If each number is decreased by 7, what will the new average be?

Correct option is B

Given:

Number of values = 7

Original average = 43

Each number is decreased by 7

Formula Used:

Sum of numbers = Average $$\times$$​ Number of values

​$$\text{New Average} = \frac{\text{Sum of new numbers}}{\text{Number of values}}$$​​

Solution:

Sum of original numbers = Original average $$\times$$Number of values

Sum of original numbers = 43$$\times$$7 = 301

Since each of the 7 numbers is decreased by 7, the total decrease in the sum is 7$$\times$$ 7 = 49.

Sum of new numbers = Sum of original numbers - Total decrease

Sum of new numbers = 301 - 49 = 252

$$\text{New Average} = \frac{\text{Sum of new numbers}}{\text{Number of values}}$$​​

New average = $$\frac{252 }{ 7}$$​ = 36

Therefore, the new average will be 36.

Alternative  Solution:

If each number in a set is decreased by the same value, the average will also decrease by that value.

New average = Original average - Decrease in each number

New average = 43 - 7 = 36

Option (B) is right.