Question

Find the mean of 25 numbers if the mean of 15 of them is 18 and the mean of the rest is 13

Answer 1

Given the mean of 15 of them is 18 and the mean of the rest is 13

And the total numbers are 25

So,

First, we need to find the sum of all numbers

the mean of 15 of them is 18

so, the sum of the 15 numbers are = 18 * 15 = 270

The rest of the numbers = 25 - 15 = 10

the mean of the rest is 13

so, the sum of the rest = 13 * 10 = 130

so, the sum of all numbers = 270 + 130 = 400

so, the mean of the all numbers =

$\frac{400}{25}=16$

So, the answer is, mean = 16