Question

The average age of a class is 19 years. While the average age of girls is 18 and that of boys is 21. If the number of girls in the class is 16, Find the number of Boys in the class?
A) 12
B) 10
C) 8
D) 6

Answer 1

Q:

The average age of a class is 19 years. While the average age of girls is 18 and that of boys is 21. If the number of girls in the class is 16, Find the number of Boys in the class?

A) 12
B) 10
C) 8
D) 6

Answer:   C) 8 

Explanation:

Let the number of boys = x
From the given data,
=> [21x + 16(18)]/(x+16) = 19
=> 21x - 19x = 19(16) - 16(18)
=> 2x = 16
=> x = 8

Therefore, the number of boys in the class = 8.