In a class, the average score of girls in an examination is 73 and that of boys is 71. The average score for the whole class is 71.8. Find the percentage of girls :

Answer: Option A

Let the number of girls = x
And, the number of boys = y
According to the question,
73x + 71y = 71.8 (x + y)
1.2x = 0.8y
$$\frac{x}{y}$$ = $$\frac{2}{3}$$
∴ Girls% = $$\frac{2}{2+3}$$ × 100
= $$\frac{2}{5}$$ × 100
= 40%