Normal Distributions

What shape is a normal distribution curve?

• Half curve
• Round curve
• Bell curve
• Square curve

According to the empirical rule, what percentage of data falls within 1 standard deviation? 

• 25%
• 68%
• 95%
• 99.7%

The center of the curve represents what value of a data set?

• μ
• δ
• Σ
• Ζ

What is the standard deviation on the graph given?

What is the mean on the graph given?

What type of distribution is pictured?

• Right skewed

• Left skewed

• Random

• Normal

A grading scale is set up for 1000 students’ test scores. It is assumed that the scores are normally distributed with a mean score of 75 and a standard deviation of 15. Calculate the score that lies -2 standard deviation from the mean.

• 60

• 475

• 45

• 9500

In an Oreo factory, the mean mass of a cookie is given as 40 g. For quality control, the standard deviation is 2 g. If 10 000 cookies were produced, how many cookies are within 2 g of the mean?

• 6800

• 9500

• 3200

• 9750

Suppose the heights of adult men are normally distributed. The heights of a sample of 30 men are shown below in inches.

65, 83, 69, 67, 69, 67, 67, 72, 85, 68, 73, 65, 67, 65, 72, 71, 67, 73, 68, 72, 61, 75, 66, 78, 65, 71, 68, 76, 67, 68

Compute the standard deviation of the sample. (Use stdev)

• 5.31

• 70

• 5.23

• 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 between 12 and 15 days?

• 68%

• 99.7%

• 95%

• 34%