10 books are placed at random in a shelf. The probability that a pair of books will always be together is\nOptions:\n(A) 1/9\n(B) 1/7\n(C) 1/5\n(D) 1/1\n(E) 1/2 Hmmm, my 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!\nRequired probability = 1/5 So, the answer is (C).
Assistant