Statistics: Frequency Tables and Histograms
Organizing data with counts, intervals, and graphs
Statistics: Frequency Tables and Histograms
Organizing data with counts, intervals, and graphs
Statistics - Grade 6-8
- 1
The number of books read by 12 students last month was: 2, 4, 1, 3, 2, 5, 4, 2, 0, 3, 1, 2. Make a frequency table for the number of books read.
Count how many times each number appears in the data set.
The frequency table is: 0 books: 1 student, 1 book: 2 students, 2 books: 4 students, 3 books: 2 students, 4 books: 2 students, and 5 books: 1 student. - 2
Use this frequency table for quiz scores: 6 points: 2 students, 7 points: 5 students, 8 points: 6 students, 9 points: 4 students, 10 points: 3 students. How many students took the quiz?
A total of 20 students took the quiz because 2 + 5 + 6 + 4 + 3 = 20. - 3
A histogram shows the following frequencies for minutes spent reading: 0-9 minutes: 3 students, 10-19 minutes: 7 students, 20-29 minutes: 5 students, 30-39 minutes: 4 students. Which interval has the greatest frequency?
Look for the tallest bar or the largest count.
The interval 10-19 minutes has the greatest frequency because it has 7 students, which is more than the other intervals. - 4
The heights of plants in centimeters are: 12, 15, 18, 21, 24, 26, 29, 31, 34, 36, 39, 40. Create a grouped frequency table using intervals 10-19, 20-29, 30-39, and 40-49.
Place each plant height into exactly one interval.
The grouped frequency table is: 10-19: 3 plants, 20-29: 4 plants, 30-39: 4 plants, and 40-49: 1 plant. - 5
A histogram has bars for test score ranges. The frequencies are 50-59: 1, 60-69: 4, 70-79: 8, 80-89: 6, and 90-99: 3. How many scores are shown in the histogram?
The histogram shows 22 scores because 1 + 4 + 8 + 6 + 3 = 22. - 6
The number of pets owned by students in a class is shown in this frequency table: 0 pets: 4 students, 1 pet: 9 students, 2 pets: 6 students, 3 pets: 3 students, 4 pets: 1 student. How many students own at least 2 pets?
At least 2 means 2 or more.
A total of 10 students own at least 2 pets because 6 + 3 + 1 = 10. - 7
A data set has these values: 5, 6, 6, 7, 8, 8, 8, 9, 10, 10. Explain why a frequency table can be more useful than a list for this data.
A frequency table can be more useful because it shows how often each value occurs, making it easier to see that 8 appears most often. - 8
A histogram groups ages into intervals of 10 years: 0-9, 10-19, 20-29, and 30-39. Explain why the bars in a histogram should touch.
A histogram is used for numerical data that is grouped into intervals.
The bars in a histogram should touch because the intervals represent continuous numerical ranges with no gaps between the groups. - 9
The number of minutes 15 students practiced an instrument is: 12, 18, 20, 22, 25, 27, 29, 31, 33, 35, 38, 40, 42, 44, 49. Make a grouped frequency table using intervals 10-19, 20-29, 30-39, and 40-49.
The grouped frequency table is: 10-19: 2 students, 20-29: 5 students, 30-39: 4 students, and 40-49: 4 students. - 10
A histogram shows the number of text messages sent in one day. The interval 0-19 has frequency 6, 20-39 has frequency 9, 40-59 has frequency 5, and 60-79 has frequency 2. How many people sent fewer than 40 messages?
Fewer than 40 includes the first two intervals.
A total of 15 people sent fewer than 40 messages because the intervals 0-19 and 20-39 have frequencies 6 and 9, and 6 + 9 = 15. - 11
A frequency table for shoe sizes shows: size 6: 2 students, size 7: 4 students, size 8: 7 students, size 9: 5 students, size 10: 2 students. Identify the mode and explain what it means.
The mode is size 8 because it has the greatest frequency. This means size 8 is the most common shoe size in the group. - 12
A student makes a histogram for the data values 1, 2, 3, 4, 5, 6, 7, 8 using intervals 1-2, 2-3, 3-4, and 4-5. Explain one problem with these intervals.
Check whether a number could belong to two different intervals.
One problem is that the intervals overlap at values such as 2, 3, and 4. Each data value should fit into only one interval, so the intervals should be written without overlap.