A box contains 4 black and 5 white balls let X denote the number of white balls in a random draw of 3 balls find E(X) and standard deviation of X

A box contains 3 black and 5 white ball and an another box contains 5 black and 3 white ball. Two same colour of ball is transferred from first box to second box and a ball drawn at random from second box. What is the probability that ball is black?

There are 30 white balls and 10 red balls in bag. 16 balls are drawn with replacement from the bag. If X be the number of white balls drawn then the value of (mean(X))/( standard deviation(X)) is equal to (A) 4sqrt3 (B) 2sqrt3 (C) 3sqrt3 (D) 3sqrt2

A bag contains 6 red, 8 black and 4 white balls. A ball is drawn at random. What is the probability that ball drawn is not black?

A bag contains 12 red and 10 white balls. 5 balls are taken from the bag at random. Find the probability that 3 balls are red and 2 balls are white.

A bag contains 2 red and 3 white balls and another bag contains 1 red and 2 white balls. If a bag is chosen at random and a ball is drawn from it, what is the probability that the ball is white ?

There are two urns A and B. Urn A contains 5 red, 4 blue, and 2 white balls, urn B contains 4 red, 3 blue, and 3 white balls. An urn is choosen at random and a ball is drawn. Probability that the ball drawn is red is

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

There are two bags, one of which contains 3 black and 4 white balls, while the other contains 4 black and 3 white balls. A fair die is cast, if the face 1 or 3 turns up, a ball is taken from the first bag, and if any other face turns up a ball is chosen from the second bag. Find the probability of choosing a black ball.

A bag A contains 2 white and 3 red balls, another bag B contains 4 white and 5 red balls. A bag is chosen at random and a ball is drawn from it. If the ball drawn is red, what is the probability that the bag B is chosen ?

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.