Question

In a large section of a Statistics class. The scores for the final are normally distributed, with a mean of 75 (µ) and a standard deviation of 8 (σ). Grades are assigned according to the following (partial) rule: • The top 10% receive “A”s. • Those with scores 64 or below receive “F”s.

(a) What is the cutoff level for “A”s (the minimum score on the exam for an “A”)? (5 pts.)

(b) What percent of students get “F”s? (5 pts.)

Answer 1

Let X denotes the score of a randomly selected student.

Here,

X ~ Normal(75, 82)

a)

b)

The percent of students get “F”s = 100*0.0846 = 8.46%