Suppose that we order the number 1,2,...,n completely randomly. What is the probability that 1 is immediately followed by 2? Solution total no of ways = (n-1)! because if we pair (21) . now the number of the sample space is n-1.thus the probability would be 1/(n-1)!.

1. Suppose that we order the number 1,2,...,n completely randomly. What is the probability that 1 is
immediately followed by 2?
Solution
total no of ways = (n-1)! because if we pair (21) . now the number of the sample
space is n-1.thus the probability would be 1/(n-1)!