Nefeli, a student in a probability class, takes a multiple-choice test with 10 questions and 3 choices per question. For each question, there are two equally likely possibilities, independent of other questions: either she knows the answer, in which case she answers the question correctly, or else she guesses the answer with probability of success 1/3. the answer to the question? 2. Given that Nefeli answered correctly 6 out of the 10 questions, what is the posterior PMF of the number of questions of which she knew the answer?
