Measures of Dispersion

Objectives: Calculate the standard deviation of a set of data. Determine what percent of a set of data fall within one (two, three) standard deviations of the mean.

Vocabulary: measures of dispersion deviation from the mean variance standard deviation	Formulas: variance: standard deviation: alternate variance: alternate variance for grouped data:

Possible Classroom Examples:

Find the mean and standard deviation of each set of data below:

a.	50	50	50	50	50
b.	46	50	50	50	46
c.	5	50	50	50	95

The weight (in pounds) of the ten Truly Amazing Dudes are as follows:

152	196	144	139	166
83	186	157	140	138

Find the mean and standard deviation of the weights.

What percent of the data lies within one standard deviation of the mean?

According to m&m-Mars blue m&ms should make up 10% of the m&ms in each plain m&m package. Below are the percent of blue m&ms for 6 packages of plain m&ms. Find the mean, the variance, and standard deviation of the percent of blue m&ms in these 6 packages.

The ages of over 52 million women who gave birth in the United States between June 1987 and June 1988 are given in the table below. Find the standard deviation of the ages of these women.

Age	Number of Women
	13,167,000
	10,839,000
	10,838,000
	9,586,000
	8,155,000