Question

A bag contains white, black or red balls. A ball is drawn from random from the bag. The probability of white balls is 3/10 , black ball is 2/5 . Then find the probability of getting red ball if the bag contains 20 black balls. Find the total no. of balls in the bag.

Answer 1

the probability of rad ball is 3/10
$\frac{2x}{5} = 20 \\ x = 50$
total no of ball is 50