Dot Plots Lesson 4.3 Core Focus on Ratios, Rates & Statistics

Warm-Up 1.42, 46, 46, 50, 58, 58, , 24, 29, 17, 19, 18, 21, What is the range of the data set in #2? mean = 52; median = 50; mode = 46, mean = 21.5; median = 20; mode = no mode Find the mean, median and mode of the following data sets.

Dot Plots Display data using dot plots. Lesson 4.3

Vocabulary Dot Plot A way to visually display the spread of data using a number line with dots equally spaced above each value. Good to Know! The number of dots represents the number of times each value is in the data set. Clusters and gaps in the data are easy to see in a dot plot.

Example 1 The dot plot below shows the number of siblings for each student in Darla’s class. Use the plot to answer the questions below. a.How many students are in Darla’s class? Count the number of dots in the dot plot. There are 25 students in Darla’s class.

Example 1 Continued… The dot plot below shows the number of siblings each student in Darla’s class has. Use the plot to answer the questions below. b.What is the mode of the number of siblings? Look for the largest stack of dots in the dot plot. There are ten people with 1 sibling. One sibling is the mode of the data set.

Example 1 Continued… The dot plot below shows the number of siblings each student in Darla’s class has. Use the plot to answer the questions below. c.How many students have either 0 siblings or 1 sibling? Count the number of dots above the 0 and 1. There are 15 students with either 1 sibling or no siblings.

Example 1 Continued… The dot plot below shows the number of siblings each student in Darla’s class has. Use the plot to answer the questions below. d.What percent of students have 3 or more siblings? There are 5 ( ) students with 3 or more siblings and 25 total students in the class. 20% of students have 3 or more siblings.

Step 1Find your height to the nearest inch and record your answer using only inches. If you are 5 feet 2 inches tall, for example, you would use the process below to convert your measurement to inches: 5 feet ∙ 12 inches per foot = 60 inches Add the 2 extra inches (60 + 2) 5’ 2” = 62 inches tall Step 2 Record the height data for all the students in your class, including your own. Step 3 What are the minimum (lowest) and maximum (highest) values in the height data? What is the range of the data? Step 4Make a number line that extends from the minimum to the maximum value in Step 3. Evenly space “tick marks” along the number line for each of the values between the minimum and maximum.

Step 5 Using your data set from Step 2, put a dot above the number line for each data value. If a data value occurs more than once, stack the dots as shown in Example 1. Step 6 Describe the spread of your data. Are your values clustered together or are they spread out? Step 7 Based on your dot plot, what is the mode of the data? How can you tell by looking at your dot plot? Step 8 What is the median of your data set? How does the median compare with the mode?

Good to Know! Michelle made the three dot plots below for her project. Which dot plot is done correctly? The first plot looks as if there are as many people with 2 bicycles as those with 0 bicycles. This is because the dots are not equally spaced above the number line. The second dot plot does not have values that are equally spaced along the number line. The third dot plot is done correctly.

Example 2 Sydney asked ten of her friends the number of states that they have visited. These were their answers: 3, 0, 1, 4, 2, 0, 2, 1, 7, 2 a. Make a dot plot of the results. The minimum value is 0 and the maximum is 7. Create a number line that extends to these values. Place dots above each value, stacking dots when a value occurs more than once.

Example 2 Continued… Sydney asked ten of her friends the number of states that they have visited. These were their answers: 3, 0, 1, 4, 2, 0, 2, 1, 7, 2 b.What are the mean, median and mode of the data? To find the mean, divide the sum of all answers by the total number of answers. The mean is 2.2.

Example 2 Continued… Sydney asked ten of her friends the number of states that they have visited. These were their answers: 3, 0, 1, 4, 2, 0, 2, 1, 7, 2 b.What are the mean, median and mode of the data? To find the median list the values from least to greatest. Find the average of the 5 th and 6 th values. The median is 2.

Example 2 Continued… Sydney asked ten of her friends the number of states that they have visited. These were their answers: 3, 0, 1, 4, 2, 0, 2, 1, 7, 2 b.What are the mean, median and mode of the data? The mode is the value which shows up most often. The mode is 2.

Communication Prompt Describe the process for creating a dot plot. Include at least 3 steps in your description.

Exit Problems 1.Draw a plot of the following data set: 8, 6, 10, 10, 9, 8, 4, 10, 8, 10, 9, 7 2. What percent of the values are greater than or equal to 8? 75%