Standard Deviation of Frequency Distributions

Using the normal distribution curve drawn above, identify the requested information below. The percent falling between 1 standard deviation above and below the mean is ________________.

• 68%

• 95%

• 81.5%

• 99.7%

Using the normal distribution curve drawn above, identify the requested information below. The percent falling between 2 standard deviations above and below the mean is ________________.

• 68%

• 95%

• 81.5%

• 99.7%

Using the normal distribution curve drawn above, identify the requested information below. The percent falling between 3 standard deviations above and below the mean is ________________.

• 68%

• 95%

• 81.5%

• 99.7%

A normal distribution has a mean of 80 and a standard deviation of 3. What percent of data points are between 74 and 80?

• 13.5%

• 47.5%

• 34%

• 68%

Approximately ​ (a)   of the data lies within 2 standard deviations of the mean.​

• 95%

• 50%

• 99.7%

• 68%

What does standard deviation represent?

• How many different variations are in the data set.

• How the population varies compared to the sample.

• How spread out each data value is from the mean.

• How often the most popular choices in a sample were picked compared to the least popular choices

What is the standard deviation on this Normal Curve?

• 6

• 12

• 34

• 18

Using the empirical rule (bell-shaped distribution). Find the percentage of scores between 30 and 38 with mean score of 34 and standard deviation of 2.

Which answer incorrectly describe the graph?

• Both distributions have equal mean

• Both distributions have equal mode

• Both distributions have equal median

•  Both distributions have equal standard deviation

Below are properties of the standard deviation, except

•   The sum up of deviation scores in a distribution will be zero.

•   If the mean changes and each data changed constantly, the standard deviation will have a new value.

•   If a constant is added to every score in a distribution, the standard deviation will not be changed.

•   If each score in a distribution is multiplied by a constant, the standard deviation will be multiplied by the same constant.