Normal Distribution Skills Check

What's the standard deviation?

• 150

• 60

• 240

• 30

A grading scale is set up for 1000 students' test scores. It is assumed the scores are normally distributed with a mean score of 75 and a standard deviation of 15. If a grade of a 60 is the lowest passing score, how many students are expected to pass the test? ​ (a)   How many students are expected to fail the test? ​ (b)  

• 840 students

• 160 students

• 84 students

• 16 students

• 877 students

• 123 students

Given a mean of 75 and a standard deviation of 7, how many students out of 500 would score between 61 and 89?

• 475

• 400

• 340

• 80

Given a mean of 75 and a standard deviation of 7, how many students out of 500 would score higher than 82?

• 475

• 170

• 237

• 80

Given a mean of 75 and a standard deviation of 7, how many students out of 500 would score between 75 and 82?

• 475

• 170

• 340

• 237

Given a mean of 75 and a standard deviation of 7, how many students out of 500 would score between 68 and 82

• 11

• 2

• 340

• 498

Given a mean of 75 and a standard deviation of 7, how many students out of 500 would score higher than 89?

• 11

• 12

• 36

• 237

Given a mean of 75 and a standard deviation of 7, how many students out of 500 would score higher than 68?

• 11

• 12

• 420

• 250

If heights of 3rd graders follow a normal distribution with a mean of 52 inches and a standard deviation of 2.5 inches, what is the z score of a 3rd grader who is 47 inches tall? 

• -5

• -2

• 2

• 5

The shelf life of a particular dairy product is normally distributed with a mean of 12 days and a standard deviation of 3 days.

About what percent of the products last between 10 and 16 days?

• 90.88%

• 25.25%

• 65.63%

• 2.5%