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There are 50 boys in a class whose average age is 12 years. There are 40 boys in another class whose average age is 15 years. What is the average age of both the classes taken together?

A.	12 years	B.	13 years 8 months
C.	13 years 4 months	D.	12 years 8 months

Answer and Explanation

Answer:13 years 4 months

Explanation:
X1 = 12 N1 = 50
X2 = 15 N2 = 40
= (X1 N1 + X2 N2) / N1 + N2
(50 × 12) + (15 × 40) / 50 + 40
= 600 + 600 / 90
= 1200 / 90
=13 1/3 years
=13 years 4 months

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