We have a training program designed to upgrade the teaching skills of special education teachers. Because the program is self-administered, teachers require different numbers of hours to complete the program. A study of past participation indicates that the mean length of time spent on the program is 500 hours and that this is normally distributed with a standard deviation of 100 hours.
Suppose the training program director wants to know the probability that a participant chosen at random would require between 550 and 650 hours to complete the required work.