Question

The average marks of $48$ students in a class is $45$. The average marks of the boys in the class is $40$ and the average marks of the girls in the class is $50$. What is the ratio between the numbers of boys and the number of girls in the class?

• A. $2;1$
• B. $11:1$
• C. $1:1$
• D. $1:2$

Answer 1

Answer: (C)

$1:1$

Total marks of $48$ students $=48x45=2160$
Let the number of boys be $B$ and the number of girls be $(48-B)$

Then total marks of boys $=40B$
Total marks of girls $=50(48-B)=2400-50B$
$\Rightarrow$ $40B+2400-50B=2160$

$\Rightarrow$ $10B=240$

$\Rightarrow$ $B=24$
Thus number of girls $=48-24=24$

Therefore, required ratio $=24:24=1:1$