Dot Plots and Distributions 14-5-EXT Lesson Presentation Holt McDougal Algebra 1 Holt Algebra 1

Objectives Create dot plots. Use a dot plot to describe the shape of a data distribution.

Vocabulary dot plot uniform distribution symmetric distribution skewed distribution

A dot plot is a data representation that uses a number line and x’s, dots, or other symbols to show frequency. Dot plots are sometimes called line plots. A dot plot gives a visual representation of the distribution, or “shape”, of the data. The dot plots in Example 1 have different shapes because the data sets are distributed differently.

Example 1 and 2 :Making a Dot Plots and Shapes of Distribution Gloria is collecting different recipes for chocolate chip cookies. The table shows the cups of flours needed in the recipes. Make a dot plot showing the data. Determine the distribution of the data and explain what the distribution means.

Example 1 and 2 : Continued Find the least and greatest number in the cups of flour data set. Then use the values to draw a number line. For each recipe, place a dot above the number line for the number of cups of flour used in the recipe. 1 2 3 Amount of Flour Recipes Cup

Example 1 and 2 : Continued The distribution is skewed to the left, which means most recipes require an amount of flour greater than the mean.

Check It Out! Example 1 The cafeteria offers items at six different prices. John counted how many items were sold at each price for one week. Make a dot plot of the data. Find the least and greatest number in the price data set. Then use the values to draw a number line. For each item, place a dot above the number line for the cost of that item.

Check It Out! Example 1 Continued 1.5 2 2.5 3.5 4.5 3 4

Check It Out! Example 2 Data for team C members are shown below. Make a dot plot and determine the type of distribution. Explain what the distribution means.

Check It Out! Example 2 Continued 3 4 5 6 The data distribution is uniform. All team members ran about the same distance.