Question

A bag contains $4$ red balls and some white balls. If the probability of drawing a red ball from the bag is $\frac{2}{5}$, find the number of white balls in the bag.

Answer 1

Let number of white balls be x

Probability of drawing red balls=$\frac{4}{4+x}=\frac{2}{5}$

On solving we get x=6

Number if white balls=6