You are expecting a call from a friend anytime between 3:00 P.M. and 5:00 P.M. At 3:20 P.M, you discover that someone accidentally left the phone off the hook. What is the probability that you missed your friend’s call?
The probability that you missed the call is 20/120 (1/6) because the time in which you expect the call is 2 hours (120 minutes), and the time that you missed is 20 minutes. So 20 out of 120 is 20/120, or 1/6 or 16.6666667%.
