A bag contains `W` white and 3 black balls. Balls are drawn one by one without replacement till all the black balls are drawn. Then find the probability that this procedure for drawing the balls will come to an end at the rth draw.

A bag contains 5 white, 7 red and 3 black balls. If three balls are drawn one by one without replacement, find the probability that none is red.

A bag contains 5 white, 7 red and 3 black balls. If three balls are drawn one by one without replacement, find the probability that none is red.

A bag contains 5 white and 4 black balls.If 3 balls are drawn at random,find the probability that at least two of them are white.

A bag contains 5 white and 3 black balls. Four balls are successively drawn out without replacement. What is the probability that they are alternately of different colours?

A bag contains 5 white and 4 black balls. If 3 balls are drawn at random, find the probability that at least two of them are white.

A box contains 7 white and 5 black balls. If 3 balls are drawn simultaneously at random with out replacement, what is the probability that they are not all of the same colour ?

A box contains 12 red and 6 white balls. Balls are drawn from the bag one at a time without replacement. If in 6 draws, there are at least 4 white balls, find the probability the exactly one white ball is drawn in the next two draws. (Binomial coefficients can be left as such.)

A box contains 7 white and 5 black balls two are drawn at random find the probability that they are not of the same colour when the balls are drawn at a time

A bag contains n white and n red balls. Pairs of balls are drawn without replacement until the bag is empty. Show that the probability that each pair consists of one white and one red ball is (2^n)/(""^(2n)C_(n))

A bag contains 5 balls. Two balls are drawn and are found to be white. What is the probability that all the balls are white?