Statistics Word Problems

A test is given that has a mean of 70 and a standard deviation of 13. If a student's Z-score is +1, the student's score before conversion was:

• 70
• 83
• 57
• Cannot be determined from the information given.

Jill's Z-score on the same test was a +3.0.  (average was 82 and SD was 4).  
What was her actual score?

• 85 %
• 79 %
• 94 %
• 40 %

A national achievement test is administered annually to 3rd graders. The test has a mean score of 100 and a standard deviation of 15. If Jane's z-score is 1.20, what was her score on the test?

• 82
• 88
• 100
• 118

An incoming freshman took her college's placement exams in French and mathematics. In French, she scored 82 and in math 86. The overall results on the French exam had a mean of 72 and a standard deviation of 8, while the mean math score was 68, with a standard deviation of 12. On which exam did she do better compared with the other freshmen?

• French exam
• Math exam

The mean life of a tire is 30,000 km. The standard deviation is 2000 km.

Then, 68% of all tires will have a life between ___________ km and __________ km.

• 28 000 km and 32 000 km

• 24 000 km and 34 000 km

• 26 000 km and 34 000 km

• 27 000 km and 31 000 km

The mean temperature in Glens Falls for the month of February is 23 degrees with a standard deviation of 4.2 degrees. What is the z-score for a temperature of 17 degrees?

• 1

• 1.43

• -1.43

• 11.5

The mean temperature in Glens Falls for the month of February is 23 degrees with a standard deviation of 4.2 degrees. Approximately what percent of days in February will have days below 23 degrees?

• 5%

• 34%

• 50%

• 6%

The number of pages that Carolyn wrote in her journal each day from Monday to Friday is shown below:

9, 8, 12, 6, 10

What is the mean number of pages she wrote per day?

• 5

• 6

• 9

• 11

The normal curve is symmetrical about the mean

• True

• False

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 12 and 15 days?

• 68%

• 34%

• 16%

• 2.5%