Concept Byte: Describing Data

For Use with Lesson 11-7

ACTIVITY

Suppose you want to know the mean number of letters in the last names of everyone listed in your local phone book. You could count the letters in every last name, but that is not very practical. Instead, you could approximate this mean by taking a sample of last names and finding the mean number of letters in only those names.

A table has four columns. The column headings are sample, number of letters, number of letters, and mean. The sample column has rows numbered 1 to 6.

An empty bar graph of numbers of samples by mean number of letters. The vertical axis has a range of 0 to 8 in intervals of 1. The horizontal axis has a range of 0 to 16 in intervals of 2.

Activity 1

Step 1 Copy the table above. Extend the table to go to Sample 20.
Step 2 Without looking, open a phone book to a random page. Place your index finger on the page, still without looking. Then, count the number of letters in the name closest to the tip of your finger. Record this number in the table in the first blank space for Sample 1. Close the phone book.
Step 3 Repeat Step 2 and record this number in the table in the second blank space for Sample 1. These two numbers make up one sample. Find the mean and record it in the table.
Step 4 Collect a total of 20 samples by repeating Steps 2 and 3.
Step 5 Copy the grid above and use the means from Data Set A to make a bar graph.
Step 6 Make a second table with space for 10 numbers in each of the 20 samples. Label this table Data Set B.
Step 7 Repeat Steps 2 and 3, but now select 10 names for each sample. Record the data in the second table.
Step 8 Copy the grid again and use the means in Data Set B to make a bar graph.
  1. Does the graph of Data Set A or the graph of Data Set B show more variation?
  2. Which data set has a greater range?
  3. Which data set has a greater standard deviation?
  4. The Law of Large Numbers states that the variation in the means of repeated samples decreases as the sample size increases. Do your results support this law?
  5. Compare and Contrast Compare your results with those of another student in the class. How are they the same? How are they different?
  6. Reasoning Suppose you conduct this experiment by collecting all of the samples from one page of the phone book. Predict how this sampling technique might affect your results.

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Table of Contents

Prentice Hall Algebra 2 Chapter 1 Expressions, Equations, and Inequalities Chapter 2 Functions, Equations, and Graphs Chapter 3 Linear Systems Chapter 4 Quadratic Functions and Equations Chapter 5 Polynomials and Polynomial Functions Chapter 6 Radical Functions and Rational Exponents Chapter 7 Exponential and Logarithmic Functions Chapter 8 Rational Functions Chapter 9 Sequences and Series Chapter 10 Quadratic Relations and Conic Sections Chapter 11 Probability and Statistics Chapter 12 Matrices Chapter 13 Periodic Functions and Trigonometry Chapter 14 Trigonometric Identities and Equations Skills Handbook English/Spanish Illustrated Glossary Selected Answers Index Acknowledgments