The time needed to complete a mid term exam at Jimma university for a given course is normally distributed with a mean of 80 minutes and a variance of 100 minutes.
1. what is the probability of completing the exam in one hour or more?
2. what is the probability that a student will complete the exam in more than 60 minutes but less than 75 minutes?
3. Assuming the class has 60 students and that the examination time is one hour and 30 minutes in length. how many students do you expect will be able to complete the exam within the allotted time?