posted by danny .
A group of five friends go out to the movies. Their average age is 15. Paco is 13 yrs. old Zoey is 16 yrs. old. What is the average age of the other three friends?
Let x = average (mean) age of three friends. Mean = sum of scores (ages) divided by the number of scores.
(16 + 13 + 3x)/5 = 15
16 + 13 + 3x = 75
3x = 75 - 29 = 46
x = 15 1/3
I hope this helps. Thanks for asking.