Topic 11: Comparing Two Populations

11-1: Statistical Measures

Part 1

Intro

A measure of center is a single, central value that summarizes a set of data.

The mean of a set of data values is the sum of the data divided by the number of data values.

data set: −5, −1, 3, 6, 8, 8, 9

Mean = 4. The mean is the measure of the center.

For an odd number of data values, the median is the middle value when the data values are arranged in numerical order.

Median = 6. The median is a measure of center.

For an even number of data values, the median is the average of the two middle items when the data values are arranged in numerical order.

Median = 6.5. The median is a measure of center.

Example Finding Mean and Median Intervals

At Yellowstone National Park, Data Girl and Ms. Adventure watch Jewel Geyser erupt. Data Girl records the time intervals between eruptions.

A dot plot.

  • a. Find the mean and median intervals between eruptions.

  • b. Using the measure of center, what inference can you make about how often Jewel Geyser erupts?


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Table of Contents

Digits, Grade 7, Volume 2, Homework Helper Unit E: Measurement and Data Unit F: Personal Financial Literacy Unit G: Step-Up Lessons English/Spanish Glossary Formulas Math Symbols Formulas Measures Properties