Find the mean of 25 numbers if the mean of 15 of them is 18 and the mean of the remaining numbers is 13.
Mean of 15 numbers = 18
Sum of 15 numbers = 18×15 = 270
Mean of remaining 10 numbers = 13
Sum of remaining 10 numbers = 10×13 = 130
Mean of 25 numbers =
=
Hence mean of 25 numbers is 16.