6 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 Additional Example 1A: Analyzing 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.A. How many people sleep less than 9 hours per night?Add the number of students in the 3-5 and 6-8 intervals.= 7878 people sleep less than 9 hours per night.
8 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.IntervalFrequencyRank(by weight)3-5251-256-85326-789-111779-9512-14596-100Determine the interval of the 50th and 51st people.The 50th and 51st persons’ hours are in the middle of the 6-8 interval. So, a good estimated is 7 hours.8
9 Check It Out: Example 1The histogram shows the results of a local 10K race. Use the histogram to answer each question.9
10 Check It Out: Example 1 Continued A. How many runners completed the race in less than 50 minutes?= 33 runnersB. 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.10
11 Additional Example 2: Making a Histogram The table below shows the number of hours students watch TV in one week. Make a histogram of the data.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 TVFrequencyNumber of Hours of TV1–3154–6177–917
12 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.201612841–3FrequencyNumber of Hours of TV154–6177–9
13 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.201612841–3FrequencyNumber of Hours of TV154–6177–9Because the intervals are equal, all of the bars should have the same width.Caution!
14 Additional Example 2 Continued Step 4: Label the axes and give the graph a title.Hours of Television Watched201612841–3FrequencyNumber of Hours of TV154–6177–9Frequency1–34–67–9Hours
15 The table shows survey results about the Check It Out: Example 2The table shows survey results about thenumber of household pet(s) students have athome. Make a histogram of the data.678912345Number of Pets
17 Lesson QuizzesStandard Lesson QuizLesson Quiz for Student Response Systems
18 Lesson Quiz: Part IUse 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.29No; 11 entrees are less than $10, but 29 are more.
19 Lesson Quiz: Part II4. 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, 15Number of StudentsNumber of Laps Run10–140–45–9864215–19Number of Laps
20 Lesson Quiz for Student Response Systems 1. How many students scored below 80?A. 6B. 13C. 19D. 37
21 Lesson Quiz for Student Response Systems 2. How many students took the final exam?A. 20B. 50C. 60D. 10021