Standard Deviation and Normal Distribution

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%

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%

1.  Which best describes the shaded part of this normal distribution graph?  

• All data that is one or higher.
• All data that is one or more standard deviations above the mean.
• All data that is between 1 and 3.
• All data that is above the mean.

Between what two standard deviations of a normal distribution contain 68% of the data?

• one below and one above
• two below and two above
• two below and zero
• zero and two above

This data is normally distributed.  What percent of the data is in the shaded region?

• 68%
• 95%
• 99.7%
• 50%

This data is normally distributed.  What percent of the data is in the shaded region?

• 68%
• 95%
• 99.7%
• 50%

This data is normally distributed.  What percent of the data is in the shaded region?

• 68%
• 32%

• 95%
• 50%

This data is normally distributed.  What percent of the data is in the shaded region?

• 68%
• 32%
• 16%
• 50%

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

• μ = population mean

• δ = population standard deviation

• Σ= sum of the data values

• Ζ = z or standard scores

On the normal curve graph, the positive standard deviations represent values ABOVE or BELOW the mean?

• ABOVE

• BELOW