Question

A humanities professor assigns letter grades on a test according to the following scheme. A: Top 13% of scores B: Scores below the top 13% and above the bottom 60% C: Scores below the top 40% and above the bottom 23% D: Scores below the top 77% and above the bottom 8% F: Bottom 8% of scores Scores on the test are normally distributed with a mean of 70 and a standard deviation of 9.6. Find the minimum score required for an A grade. Round your answer to the nearest whole number, if necessary

Answer 1

81

Explanation:

Given data:

mean μ = 70.

standard deviation σ, 9.6.

P(Z < 1.123) = 0.13

z = 1.13

Use the z-score formula,

x = z×σ +μ

Substitute the values in the above equation.

x = 1.13 9.6 + 70 = 81

The minimum score required for an A grade is = 81