An economics test is taken by a large group of students. The test scores are normally distributed with mean μ = 70 points.
a. Find the population standard deviation σ, if it was found that 93.32% of students received a score of less than 85 points.
Answer:
b. What is the probability that a randomly chosen student scores more than 80 points on this test? (hint: by using σ calculated in part (a)) (round your answers to 2 decimal places)
Answer:
c. For a random sample of n = 200 students, find the probability that more than 120 scores at most 80 points on this test. (hint: P(Y > 120) = ? Where Y = number of students who score at most 80 points on this test and π = P(X ≤ 80))