Part (a) The distribution of W is basically the Probability Mass Function (PMF) of W. So write out the PMF and from there you can determine the type of distribution (eg. Binomial, Geometric, etc.)
Part(b) C: correct answers; W: wrong answers; total questions = n Therefore C+W = n or C = n-W Using the abovementioned relation and your answer to part (a) you can find both the PMF and E[C].
hint: P(C=c) = P(W=n-c), then apply PMF from (a)
