Subject: General Aptitude · Chapter: Average · Exam: 2008 · Marks: · Difficulty:
The average score of girls in class X examination in a school is 73 and that of boys is 71. The average score in class X of that school is 71.8. Find the percentage of the number of girls and boys in class X of the school.
Answer
Answer (as printed):
Explanation
Let the number of boys in the class be $x$ and the number of girls be $y$. $$\begin{aligned} & \text { Then, } 71 x+73 y=71.8(x+y) \Rightarrow 0.8 x=1.2 y \Rightarrow x=\frac{3}{2} y . \\ & \text { Percentage of boys }=\left[\frac{x}{(x+y)} \times 100\right] \%=\left[\frac{\frac{3}{2} y}{\left(\frac{3}{2} y+y\right)} \times 100\right] \% \\ & =\left(\frac{3 y}{2} \times \frac{2}{5 y} \times 100\right) \%=60 \% . \end{aligned}$$ Percentage of girls $=(100-60) \%=40 \%$.
Explanation as extracted from the printed page; notation may be imperfect.