The mean age of a class of twenty five students is 23.4 years. How old would a twenty sixth student have to be for the mean age of the class to be 24.0 years?

Answer 1

The sum of ages of the 25 students = 25(23.4) = 585

the sum of ages of 26 students = 26(24) = 624

So the 26th student must be 624-585 or 39 years old