A set of final examination grades in a calculus course was found to be normally distributed with a mean of 69 and a standard deviation of 9.What is the probability of getting a grade of 91 or less on this exam?
A)1.00
B)0.50
C)0.0073
D).9927

Question

Quizplus · Accepted Answer

Using the normal distribution table or a calculator, we can find the z-score for a grade of 91 as follows:

z = (91 - 69) / 9 = 2.44

Then, looking at the standard normal distribution table, the area to the left of a z-score of 2.44 is 0.9927. Therefore, the probability of getting a grade of 91 or less is 0.9927 or 99.27%.

A Set of Final Examination Grades in a Calculus Course