A friend of yours has just seen your exam results and has telephoned to tell you whether you have passed or failed. Alas the telephone connection is so badthat if yourfriendsays “pass” youmistakethat for “fail” 3out of10 times and if your friend says “fail” you mistake that for “pass” 1 out of 10 times. Before talking to your friend you were 60% confidentthat you had passed the exam. How confident are you of having passed the exam if you heard your friend say you have passed?