Astudent takes a multiple choice test. each question has n answers. if the student knows the answer to a question, the student gives the right answer, and otherwise guesses uniformly and at random. the student knows the answer to 70% of the questions. write k for the event a student knows the answer to a question and r for the event the student answers the question correctly. a) what is p(k)? b) what is p(rik)? c) what is p(kr), as a function of n? d) what values of n will ensure that p(k|r) > 99%?