7-3 Histograms Course 2 Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day Lesson Quizzes Lesson Quizzes

7-3 Histograms Warm Up Find the mean, median, mode, and range for the data set. 35, 45, 48, 53, 53, 27, 66, 36, 24 43; 45; 53; 42

7-3 Histograms Problem of the Day Which number does not belong with the others? Why? 81, 64, 36, 27, 49 Possible answer: 27; the others are perfect squares.

7-3 Histograms Prep for MA.7.S.6.2 Construct and analyze histograms…. Sunshine State Standards

7-3 Histograms Vocabulary histogram

7-3 Histograms A histogram is a bar graph that shows the frequency of data within equal intervals. There is no space between the bars in a histogram.

7-3 Histograms The histogram shows the results of a survey asking people the number of hours they sleep per night. Use the histogram to answer each question. Additional Example 1A: Analyzing Histograms A. How many people sleep less than 9 hours per night? Add the number of students in the 3-5 and 6-8 intervals = people sleep less than 9 hours per night.

7-3 Histograms Additional Example 1B: Analyzing Histograms B. What is the approximate median number of hours people sleep per night? Since 100 people were surveyed, the median is the mean of the 50th and 51st persons’ hours. The 50th and 51st persons’ hours are in the middle of the 6-8 interval. So, a good estimated is 7 hours. IntervalFrequencyRank (by weight) Determine the interval of the 50th and 51st people.

7-3 Histograms The histogram shows the results of a local 10K race. Use the histogram to answer each question. Check It Out: Example 1

7-3 Histograms Check It Out: Example 1 Continued A. How many runners completed the race in less than 50 minutes? = 33 runners B. What is the approximate median time people ran the race? There are 50 runners total, so the median is between the 25th and 26th times when the runners’ times are ranked from least to greatest. This is in the middle of the 45:00-49:59 group, so 47:30 is a good estimate for the median.

7-3 Histograms The table below shows the number of hours students watch TV in one week. Make a histogram of the data. Additional Example 2: Making a Histogram Step 1: Make a frequency table of the data. Be sure to use equal intervals. 6 /// 7 //// //// 8 /// 9 //// 1 // 2 //// 3 //// //// 4 //// / 5 //// /// Number of Hours of TV 1–3 Frequency Number of Hours of TV 15 4–6 17 7–9 17

7-3 Histograms Additional Example 2 Continued Step 2: Choose an appropriate scale and interval for the vertical axis. The greatest value on the scale should be at least as great as the greatest frequency. 1–3 Frequency Number of Hours of TV 15 4–6 17 7–

7-3 Histograms Additional Example 2 Continued Step 3: Draw a bar graph for each interval. The height of the bar is the frequency for that interval. Bars must touch but not overlap. 1–3 Frequency Number of Hours of TV 15 4–6 17 7– Because the intervals are equal, all of the bars should have the same width. Caution!

7-3 Histograms Additional Example 2 Continued Step 4: Label the axes and give the graph a title. 1–3 Frequency Number of Hours of TV 15 4–6 17 7– –3 4–6 7–9 Hours of Television Watched Frequency Hours

7-3 Histograms The table shows survey results about the number of household pet(s) students have at home. Make a histogram of the data. Check It Out: Example Number of Pets

7-3 Histograms Check It Out: Example 2 Continued

7-3 Histograms Standard Lesson Quiz Lesson Quizzes Lesson Quiz for Student Response Systems

7-3 Histograms Lesson Quiz: Part I Use the histogram to answer each question. 1. How many entrees cost $10 or more? 2. Sarah wants to go to a restaurant where most entrees are less than $10. Should she go to the restaurant whose entrees are represented in the graph? Explain. 29 No; 11 entrees are less than $10, but 29 are more.

7-3 Histograms Lesson Quiz: Part II 4. The list shows the number of laps students ran one day. Make a histogram of the data. 4, 7, 9, 12, 3, 6, 10, 15, 12, 5, 18, 2, 5, 10, 7, 12, 11, 15 Number of Students Number of Laps Run 10–14 0–4 5– –19 Number of Laps

7-3 Histograms Lesson Quiz for Student Response Systems 1. How many students scored below 80? A. 6 B. 13 C. 19 D. 37

7-3 Histograms Lesson Quiz for Student Response Systems 2. How many students took the final exam? A. 20 B. 50 C. 60 D. 100