A large statistics class took an exam. The scores followed a normal curve with mean 78 and standard deviation 10. Students who scored 90 or above got an A on the exam. Those who scored between 80 and 90 got a B, between 70 and 80 a C, between 60 and 70 a D, and below 60 an F.
a. Estimate the percentage of students who earned an A on the exam.
b. Estimate the percentage of students who earned a B on the exam.
c. Estimate the percentage of students who earned a C on the exam.
d. Estimate the percentage of students who earned a D on the exam.
e. Estimate the percentage of students who earned an F on the exam.