Solve the problem.
-Scores on a test are approximately normally distributed with a mean of 70 and a standard deviation of 9. The teacher wants to give A's to the top 10% of students and B's to the next 23%. What is the
Bottom cutoff for a B grade? Round your answer to the nearest whole number.
A)71
B)74
C)66
D)76

Question

Quizplus · Accepted Answer

To find the cutoff for a B grade, we need to determine the score that separates the top 33% (10% for A's and 23% for B's) from the rest. Using the standard normal distribution table, the z-score for the 67th percentile is approximately 0.44. Using the formula: score = mean + (z-score * standard deviation), we get 70 + (0.44 * 9) = 73.96, which rounds to 74.

Solve the Problem. -Scores on a Test Are Approximately Normally Distributed with a Distributed