Q8 of 174 Page 577

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.


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