From an urn containing a white b black balls, k balls are drawn and laid aside, their colour unnoted. Then one more ball is drawn. Find the probability that it is white assuming that `klta,b.`

An urn contains 6 white and 4 black balls. A fair die is rolled and that number of balls we chosen from the urn. Find the probability that the balls selected are white.

An urn contains 8 white balls and 6 black balls. Two balls are drawn from the urn one after another without replacement. What is the probability that both the drawn balls are white?

A bag contains 10 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.

An urn contains 10 red and 8 white balls. One ball is drawn at random. Find the probability that the ball drawn is white .