Christine has always been weak in mathematics. Based on her performance prior to the final exam in Calculus, there is a 40%

chance that she will fail the course if she does not have a tutor.

W ith a tutor, her probability o f failing decreases to 10%. There is only a 50% chance that she w ill find a tu to r at such short notice.

a. W hat is the probability th a t Christine fails the course?

b. Christine ends up failing the course. W hat is the probability th a t she had found a tutor?  P-258