Given the stream of consciousness rationale, provide a reasonable question and answer. Rationale: 10 books can be rearranged in 10! ways consider the two books taken as a pair then number of favourable ways of getting these two books together is 9! 2!
Required probability = 1/5
The question and answer:
10 books are placed at random in a shelf. The probability that a pair of books will always be together is -
Options:
(A) 1/5
(B) 1/3
(C) 1/4
(D) 118/2
(E) 21/4
The answer is (C)