Find the mean of 25 given numbers when the mean of 10 of them is 13 and the mean of the remaining numbers is 18.

Solution:

Mean of 10 numbers = 13

Sum of numbers = 13×10 = 130

Mean of remaining 15 numbers = 18

Sum of numbers = 15×18 = 270

Sum of all numbers = 130+270 = 400

Mean = sum of numbers/25 = 400/25 = 16

Hence the mean of 25 numbers is 16.