grading scale problem

(First part)
"Grades are assigned on the following scale: 90-100 =A; 80-89=B; 70-79=C; 60-69=D; BELOW 60=F... Assume that grades follow a normal distribution with a mean score of 75 and a standard deviation of 8. In a class of 36 students, how many students will receive an A? a B? a C? a D? an F?"
(Second part)
"Provide one mathematical reason why our assumption in 1 is reasonable."
(Third part)
"Provide at least one mathematical reason why our assumption in 1 is not reasonable."



I'd appreciate any help I can get! I'm not sure where to even start with this one. I feel like I need to know how many students are in the class, or something. Please help!

Have you considered the Emerical Rule?

68% of scores (0.68*36 = 24.48), or 24 students will receive a grade between 75-8 = 67 and 75+8 = 83

What might be next?

Part 3 - It might be a bad idea because it denies the possibility that you have a wonderful class such that every student aces the pathetic exam and it still forces you to fail someone.