Question

A class consists of $50$ students out of which $30$ are girls.The mean of marks scored by girls in a test is $71$ (out of 100) and the mean score of the whole class is $71.8$. Find the mean of marks scored by boys in the test.

• A. $73$
• B. $76$
• C. $74$
• D. $72$

Answer 1

The correct option is D $72$

The $mean$ of $30$ girls $=73$

The $total$ students$=50$

out of that $30$ are girls.

$Totalno$ of boys$=50-30=20$

The $score$ of girls $=73\times 30=2190$

The $score$ of boys$=71\times 20=1420$

The $meanscore$ of total class $=\frac{2190+1420}{50}=\frac{361}{5}=72.2$