Question

A humanities professor assigns letter grades on a test according to the following scheme. A: Top 12% 12% of scores B: Scores below the top 12% 12% and above the bottom 62% 62% C: Scores below the top 38% 38% and above the bottom 19% 19% D: Scores below the top 81% 81% and above the bottom 9% 9% F: Bottom 9% 9% of scores Scores on the test are normally distributed with a mean of 77.5 77.5 and a standard deviation of 8.6 8.6 . Find the minimum score required for an A grade. Round your answer to the nearest whole number, if necessary.

Answer 1

Solution; We are given:

We have to first find the z-value corresponding to area = 1 - 0.12 = 0.88. Using the standard normal table, we have:

Now using the z-score formula, we have:

Therefore, the minimum score required for an A grade is 88