Possible error: Chapter 3, Problem 8

[bryzhang]

I may have misunderstood something, but I believe the first case should be:

$P(x = k) = \frac{\binom{k-1}{4}}{\binom{99}{4}} * \frac{1}{100}$

That is, the probability that you pick the given card, and the probability that, for the remaining four cards, you only pick lower cards.