Discrete Probability....... probability of events?

[racewithferrari]

Discrete Probability....... probability of events?

What is the probability of these events when we randomly select a permutation of {1,2,....n} where n>=4?

a) 1 precedes 2
b) 2 precedes 1

 

[arthur ohlsten]

a) 1/2
b) 1/2

Arthur