Question

A bag containing 15 white balls and some black balls if the probability of drawing a black ball from the bag is thrice that of the drawing a white ball find the number of black balls in the bag

Answer 1

Answer:

White balls = 15

Black balls = X

So ... According to the question

3x = 15 ( black is 3 times the white balls )

X = 5

Answer 2

white ball=15 black ball=x
total balls=15+x
According to question,
P(drawing a black ball) 3=P(drawing a white ball)
{x/15+x}3=15/15+x
3x=15
x=5
therefore, number of black balls in the bag=5