There are 5 white and 3 black balls in a box. 3 balls are taken at random from the box. Find the expected number of black balls.

A box contains 4 white and 6 red balls if 2 balls are drawn at random find the expectation of the number of red balls

A box contains 5 white balls and some black balls A ball is taken from the box a) What is the number of black balls If the probability of black ball is twice the probability of white balls

There are two boxes. In the first box there are 4 white, 5 black balls. In the second box there are 5 white, 4 black balls. A ball at random is drawn from the first box and transferred to the second box. Then if a ball is drawn at random from the second box, the probability for the drawn ball to be white is

A box contains 6 white balls and 4 black balls, A ball is drawn at random from the box. What is the probability that the ball is white.

A box contains 7 red balls, 8 green balls and 5 white balls. A ball is drawn at random from the box. Find the probability that the ball is white.

A box contains 7 red balls, 8 green balls and 5 white balls. A ball is drawn at random from the box. Find the probability that the ball is white.

A box contains 9 red, 7 white and 4 black balls. A bait is drawn at random from the bdx. probability that the ball drawn is (ii) white or black