Question

The average age of a class is $15.8$ years. The average age of the boys in the class is $16.4$ years while that of the girls is $15.4$ years. What is the ratio of boys to girls in the class?

• A. $1:2$
• B. $2:3$
• C. $3:4$
• D. $3:5$

Answer 1

The correct option is B $2:3$

Let the number of boys and girls in the class be $x$ and $y$ respectively.
Total age of the class $=15.8\times (x+y)$
$=(15.8x+15.8y)$ years
Total age of the boys $=16.4x$ years
Total age of girls $=15.4y$ years
$\therefore 16.4x+15.4y=15.8x+15.8y$
$\Rightarrow 16.4x-15.8x=15.8y-15.4y$
$\Rightarrow 0.6x=0.4y$

$\Rightarrow \frac{x}{y}=\frac{4}{6}=\frac{2}{3}$