The time needed to finish math examination is bell-shaped with a mean of 60 minutes and a standard deviation of 15 minutes.

a) What percentage of students will complete the exam in 30 minutes or less?

%

b) Assume that the class has 130 students and that the examination period is 90 minutes in length. How many students do you expect will not be able to complete the exam in the allotted time? Round answer to the nearest whole number.

c) A student is classified as extremely "efficient" if the amount of time spent on the exam is the lowest 2.5% for the distribution. What is the upper limit for the time it takes an extremely "efficient" student to finish the exam?