Some question: 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
Some stream of consciousness:
user
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 answer: (C).
assistant