If a statistics class has a distribution of grades with a mean of 70 and standard deviation of 15, what is the probability of a student scoring between a 70 and 90?
A) .20
B) .41
C) .50
D) .61

Question

Quizplus · Accepted Answer

The probability of a student scoring between a 70 and 90 is 0.41, which is choice B. This can be calculated using the normal distribution, which is a bell-shaped curve that describes the distribution of many random variables. The mean of the distribution is the average value, and the standard deviation is a measure of how spread out the data is. The probability of a student scoring between a 70 and 90 is the area under the normal distribution curve between those two values. This area can be calculated using a standard normal distribution table or a calculator.

If a Statistics Class Has a Distribution of Grades with a Mean