Question

The average age of students of a class is 15.8 years. The average age of boys in the class is 16.4 years and that of the girls is 15.4 years, The ratio of the number of boys to the number of girls in the class is :

A) 1 : 2 B) 2 : 3 C) 3 : 4 D) 4 : 5

Answer 1

Step-by-step explanation:

Let the number of boys and girls in the class be x and y respectively.

Total age of the class

= 15.8 × ( x + y )

= (15.8x + 15.8y ) years

Total age of boys = 16.4x years

Total age of girls = 15.4y years

==> 16.4x + 15.4y = 15.8x + 15.8y

==> 16.4x - 15.8x = 15.8y - 15.4y

==> 0.6x = 0.4y

$\frac{x}{y} = \: \frac{0.4}{0.6} = \: \frac{4}{6} = \: \frac{2}{3}$

Hence ,

the ratio of the number of boys to

number of girls in the class is

x : y = 2:3