Question

The mean of 15 numbers is 9. If each observation is multipled by 4, what will be the new mean? Give reason for your answer.

Answer 1

Answer: 36

Step-by-step explanation:new mean = 4×( sum xi)/15 = 4×9 = 36

Answer 2

GIVEN:

Mean of 15 numbers = 9

We know that,

Mean :

$\frac{sum \: of \: all \: observations}{number \: of \: observations}$

Let the sum of all observations be x

15 = x/9

15 × 9 = x

x = 135

Sum of all Observations = 135

When each number is multiples with 4 then the sum of all observations,

= 135 × 4

= 540

New mean = 540/15

= 36

Method - 2 :

Mean of 15 numbers = 9

When each observation is multiplied with 4 then new mean,

= 9 × 4

= 36

Therefore, new mean is 36.