Question

a box contains some black balls and 30 white balls if the probability of drawing a black ball is two-fifth of that drawing a white ball find the number of black balls

Answer 1

Answer:

According to the problem, the probability of drawing a black ball is two-fifths of the probability of drawing a white ball. So, we get P(b)=25×P(a) ---(3). We know that the sum of the probabilities of drawing white and black balls is 1