Question

A humanities professor assigns letter grades on a test according to the following scheme. A: Top 12% of scores B: Scores below the top 12% and above the bottom 63% C: Scores below the top 37% and above the bottom 15% D: Scores below the top 85% and above the bottom 9% F: Bottom 9% of scores Scores on the test are normally distributed with a mean of 68 and a standard deviation of 7.6. Find the minimum score required for an A grade. Round your answer to the nearest whole number, if necessary.A humanities professor assigns letter grades on a test according to the following scheme. A: Top 12% of scores B: Scores below the top 12% and above the bottom 63% C: Scores below the top 37% and above the bottom 15% D: Scores below the top 85% and above the bottom 9% F: Bottom 9% of scores Scores on the test are normally distributed with a mean of 68 and a standard deviation of 7.6. Find the minimum score required for an A grade. Round your answer to the nearest whole number, if necessary.

Answer 1

The minmum score of grade A has 0.12 area to its right and 1 - 0.12 = 0.88 area to its left. That is we need to find 88th percentile of score distribution.

Hence, the minimum score for grade A is 77.