23. Time to Complete Final Exam. The time needed to complete a final examination in a particular college course is normally distributed with a mean of 80 minutes and a standard deviation of 10 minutes. Answer the following questions. (d) Suppose a student is to write the final exam of another course right after, and the time needed to complete this exam is normally distributed with a mean 86 minutes and a standard deviation of 15 minutes. What is the probability that the student will spend less than three hours in total to complete the two exams?