I've been having some difficulty with the problem below:
For part a I said that the probability is $\frac{(n-1)^k}{n^k}$ since the bottom represents the total number of ways of choosing a student and the top whenever a student is not chosen. However, I'm not sure if it's right. For part b, am I supposed to plug in $2n\log(n)$ for $k$ for the answer that I got from part A?