Nafeli is taking a multiple-choice exam with 10 questions and 3 choices per question. For eachquestion, there are two equally likely possibilities, independent of other questions. In the firstpossibility, she knows the answer, in which case she answers the question correctly. In the secondpossibility, she guesses the answer with probability of success 1/3.1. Given that Nafeli answered correctly the first question, what is the probability that she knewthe answer to that question