試題詳解

135. A student takes an examination consisting of 20 true-false questions. The student knows the answer to N of the questions, which are answered correctly, and guesses the answers to the rest. The conditional probability that the student knows the answer to a question, given that the student answered it correctly, is 0.824..
Calculate N.
(A) 8
(B) 10
(C) 14
(D) 16
(E) 18