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) 1/6\n(C) 1/5\n(D) 1/0\n(E) 1/1
Let's be accurate as possible. Think before you answer.
(C)
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.

Therefore, the answer is (C)