Question

Assume that a set of test scores is normally distributed with a mean of 100 and a standard deviation of 20. Use the 68-95-99.7 rule to find the following quantities:
Suggest you make a drawing and label first…
a.Percentage of scores less than 100b.Relative frequency of scores less than 120c.Percentage of scores less than 140d.Percentage of scores less than 80e.Relative frequency of scores less than 60f.Percentage of scores greater than 1

Answer 1

a. In a normal distribution, mean = median = mode. Hint: What is median?

b. median + 1/2(68)

Use similar process for other questions.

f. all of the scores > 1. (> = greater than)

Answer 2

The mean is 100 with standard deviation of 15.the results come very close to fitting a normal curve
Find the percent of students whose score wil fall in less than 100