In a school with 600 students, the average age of the boys is 12 years and that of the girls is 11 years. If the average of the school is 11 years 9 months, then the average the number of girls in the school is :
A. 150 B. 250 C. 350 D. 450 Answer: Option AShow Answer
Solution(By Apex Team)
Let the number of girls be x
Then, number of boys = (600 – x)
Then,
$\begin{array}{l}\left(11\frac{3}{4}\times600\right)=11x+12(600-x)\\
\Leftrightarrow x=7200-7050\\
\Leftrightarrow x=150\end{array}$
[oceanwp_library id=”3669″]
HI 
EN 