Question: 1. Find the probabilities pr that in a sample of r random digits no two are equal. Estimate the numerical value of P10, using Stirling's formula.
2. What is the probability that among k random digits
(a) 0 does not appear;
(b) 1 does not appear;
(c) neither 0 nor 1 appears;
(d) at least one of the two digits 0 and 1 does not appear? Let A and B represent the events in (a) and (b). Express the other events in terms of A and B.