Question

a bag contain 5 white ball, 7 red ball, and 9 yellow ball and three ball are drawn at a time, what is the probability of getting (a) only red (b) both white and yellow balls​

Answer 1

In the bag we’ve 5 white, 7 red & 3 black.

So there is total 5+3+7=15 balls.

Number of balls which are not red is = 5+3=8

In the first draw, the probability the ball is not red is =8/15

Now after first draw a ball which is not red ie either white or black is picked. So no. of balls in the bag which is not red= 8–1=7 & total balls in bag =15–1=14

Picked ball is not red in second draw is = 7/14=1/2

Similarly picked ball not red in 3rd draw is = 6/13

So probability that none of the balls in first 3 draws are red (assuming without repetition) is = (8/15)*(1/2)*(6/13)=24/195=8/65