Z-Scores and Probabilities

The sign of the z-score indicates whether the location is above(positive) or below(negative) the mean.

• True

• False

Find the z-score value corresponding if the location is below the mean by 2 standard deviations

• +2.00

• -2.00

• +1.25

• -1.00

• It means you did better than zero people.

• It means you scored the same grade as the average grade.

• It means you earned a zero on the quiz.

• It means the average score was a zero.

Use the image of the normal graph provided. What is the value of the mean?

• 6

• 34

• 52

• 70

Use the image of the normal graph provided. What is the value of the standard deviation?

• 6

• 12

• 36

• 18

At a company, the data set containing the ages of applicants for a particular job was 30 years old, and the standard deviation of the data set was 3.5 years. Which is closest to the percent of applicants that were 21 years old or younger?

• 0.5%

• 2.0%

• 2.57%

• 9.0%

For Mrs. V: mean = 55 and standard deviation = 19

For Mr. T: mean = 33 and standard deviation = 10.5

What percent of students scored 42 or higher in Mr. T's class? Round your answer to the nearest whole number, do not put the percent sign.

For Mrs. V: mean = 55 and standard deviation = 19

For Mr. T: mean = 33 and standard deviation = 10.5

What percent of students scored 80 or higher in Mrs. V's class? Round your answer to the nearest whole number, do not put a percent sign.

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%
• 68%

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 6 days or less?

• 68%
• 34%
• 16%
• 2.5%