Question

7 white balls and 3 black balls are kept randomly in order. Find the probability that no two adjacent balls are black. A. 1 2 B. 7 15 C. 2 15 D. 1 3 Select the correct answer from above options

Answer 1

Correct Answer - B 7 white and 3 black balls can be arranged in a row in 10! 3!7! ways. When 7 white balls are arranged in a row there are 8 place in between. In these 8 places 3 black balls can be arranged in .8C3 ways. ∴ Required probability = .8C3 10! 3!7! = 7 15