Question

The mean of 5 number is 11 . If four of them are 3,8,10,15, find the fifth number

Answer 1

The average/mean is calculated as follows.

Average=Sum/Total number

We are given total 5 numbers and average 5 , we have to find out fifth number when we are given four numbers too.

let the fifth number be x.

According to question,

(3+8+10+15+x)/5=11

=> 36 + x /5 = 11

=> x/5 =11-36

=> x/5 = -25

=> x = -25 × 5

=> x = -125

So, fifth number is -125