We have the training program designed to the 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.
What is the probability that the candidate selected at random will take between 500 and 650 hours to complete the program?