A student either knows the answer or guesses on a multiple choice test.

Let

be the probability the student knows the answer and

be the probability the student guesses.

Assume a student that guesses will be right with a probability of

. (where

is the number of multiple choice alternatives.

What is the probability that the student knew the answer to a question given that it was answered correctly?

I am pretty sure this problem uses Bayes Thm, but I am not sure where to begin. Any help please? Thank you.

-Jame