Question

a box contain 15 white and some black coloured ball. the probability of getting black coloured ball is three times the probability of getting white coloured ball . then find the number of black coloured ball. ​

Answer 1

Answer:

Let number of black coloured balls be x.

Total number of balls = 15 + x

According to statement

Probability of getting black coloured ball = three times the probability of getting white coloured ball

$\frac{x}{x + 15} = 3 \times \frac{15}{x + 15} \\ x = 45$