A multiple choice examination has $10$ questions, each of which has $4$ possible answers.Suppose that for each question a student knows the correct answer with probability $0.8$ and guesses with probability $0.2$. Find the probability that the student will correctly answer exactly $9$ questions?
P(Exactly 9 correct answers)= $10$ * $(0.8)^9$ * $0.2$
The given solution answer is $0.3474$.
How should I solve this?