The average age of students of a class is 17.6 years. The average age of boys in the class is 18.2 years and that of the girls is 16.3 years. The ratio of the number of the boys to the number of girls in the class is:

Solution: Let us assume no. of  boys is x, girls are ‘y’.

 Age of  boys  = 18.2x

 Age of  girls = 16.3y

Age of  total students 

$\therefore$Age of  total students $\Rightarrow$17.6  years

$\frac{\left(18.2\right)x+\left(16.3\right)y}{x+y}=17.6\Rightarrow 18.2x+16.3y=17.6(x+y)$

$18.2x-17.6x=17.6y-16.3y$

$0.6x=1.3y$

$6x=13y$

$\frac{x}{y}=\frac{13}{6}$