1. The time needed to complete a final exam is normally distributed with a mean of 50 and a standard deviation of 7.
a. What is the probability of completing the exam is 40 minutes or less?
b. What is the probability of completing the exam in more than 55 minutes but less 60 minutes?
c. If the class has 30 students and the examination period is 50 minutes, how many students do you expect will be unable to complete the final exam?