Seven white and 3 black balls are placed in a row. What is the probability if two black balls do not occur together ?

A bag contains 5 red, 6 white and 7 black balls. Two balls are drawn at random. what is the probability that both balls are red or both are black?

The number of ways of arranging m white and n black balls in a row (mgtn) so that no two black are placed together, is

An urn contains three white, six red and four black balls. Two balls are selected at random. What is the probability that one ball is red and other is white, given that they are of different colour ?

In how many ways 4 different white balls and 6 different black balls be arranged in a row that no two white balls are together ?

7 white balls and 3 black balls are kept randomly in order. Find the probability that no two adjacent balls are black.

In how many ways can 12 white and 8 black balls be arranged in a row if no two black balls are together?

There are 4 white and 6 black balls in a bag. Two balls are drawn at random. Find the probability that both balls drawn are black.

A bag A contains 3 white and 2 black balls and another bag B contains 2 white and 4 black balls. A bag and a ball out of it are picked at random. What is the probability that the ball is white?

If from each of the three boxes containing 3 white and 1 black, 2 white and 2 black, 1 white and 3 black balls, one ball is drawn at random, then the probability that 2 white and 1 black balls will be drawn, is

If from each of the three boxes containing 3 white and 1 black, 2 white and 2 black, 1 white and 3 black balls, one ball is drawn at random, then the probability that 2 white and 1 black balls will be drawn, is