Two balls are chosen randomly from an urn containing 8 white and 4 black balls. Suppose that we win Rs 20 for each black ball selected and we lose Rs 10 for each white ball selected . Find the expected winning amout and variance.

Two balls are chosen randomly from an urn containing 6 white and 4 black balls . Suppose that we win ₹ 30 for each black ball selected and we lose ₹ 20 for each white ball selected. If X denotes the winning amount then find the values of X and number of points in its inverse images .

Two balls are chosen randomly from an urn containing 6 red and 8 black balls. Suppose that we win Rs. 15 for each red ball selected and we lose Rs. 10 for each black ball selected. X denotes the winning amount, then find the values of X and number of points in its inverse images.

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.

Six balls are drawn successively from an urn containing 7 red and 9 black balls. Tell whether or not the trials of drawing balls are Bernoulli trials when after each draw the ball drawn is i. replaced ii. not replaced in the urn.

Six balls are drawn successively from an urn containing 7 red and 9 black balls. Tell whether or not the trials of drawing balls are Bernoulli trials when after each draw the ball drawn is (i) replaced (ii) not replaced in the urn.

A bag contain 5 whtie and some black balls. If the probability of drawing a black ball from the bag is twice the probability of drawing a white ball then find the number of black balls.

Three balls are to be chosen from a box contaning 3 red ,2 white and 4 blue balls.Find the probability that all the three balls are of different colour.