Question

A random sample of six integers in the interval [1,42] is to be drawn.
The numbers are selected randomly, one after the other, and repeats
are allowed. What is the probability the six numbers in the sample will
all be different?

Answer 1

number of all possible cases with repetition is
42^6

number of cases where they are all different
= 42x41x40x39x38x37

Prob (all different) = (42x41x40x39x38x37)/42^6
= appr .688