In answering a question on a multiple choice test, a student either knows the answer or guesses. Let n3/4 be the probability that he knows the answer and 1/4be the probability that he guesses. Assuming that a student who guesses at the answer will be correct with probability 1/4 . What is the probability that the student
knows the answer given that he answered it correctly?
33 P(he knows ans).P(It is correct|he knows)
P(he knows ans).P(It is correct|he knows)+P(He Guesse).P(is correct|he gussess)
P(He knows ans)=3/4
P(It is correct|he knows)=1
P(He gusses)=1/4
P(It is correct|he knows))=1/4
Hence the answer
3/4*1
1/4*1/4+3/4*1
24yup..................priyam is rite..........only a fool will mark wrong the question he knows
