Question

If $\frac{4}{7}$ students of a class of strength $70$ are boys, then the number of girls equals ____.

• A. $40$
• B. $30$
• C. $20$
• D. $50$

Answer 1

The correct option is B $30$

Total strength of class $=70$

Fraction of students who are boys $=\frac{4}{7}$

$\Rightarrow$ Fraction of students who are girls $=1-\frac{4}{7}=\frac{3}{7}$

$\Rightarrow$ Total number of girls in class $=\frac{3}{7}\times 70=30$