Virginia SOL Math / Grade 7 / Probability & Statistics

7.PS.2

Data Cycle with Histograms

What you'll learn

  • Organize data into equal intervals for a histogram
  • Read and interpret a histogram
  • Compare a histogram with a bar graph

Words to know

Histogram —
a graph that shows data grouped into equal number intervals
Interval —
an equal range of values, such as 0 to 9
Frequency —
how many data values fall in an interval
Data cycle —
the steps of asking, collecting, organizing, and interpreting data
Bar graph —
a graph that compares separate categories with bars

Why it matters Histograms reveal the shape of numerical data, such as test scores or ages, showing where values cluster and how they spread.

Worked examples

Model ItI do

A histogram has intervals 0 to 9, 10 to 19, and 20 to 29 with frequencies 5, 8, and 3. How many data values are there in all?

Add the frequencies of all intervals: 5 + 8 + 3 = 16. There are 16 data values in all.

Try It TogetherWe do

Using the same histogram, which interval has the most data values?

Compare the frequencies: 5, 8, and 3. The largest is 8, so the interval 10 to 19 has the most data values.

Now YouYou do

A histogram has intervals with frequencies 4, 7, 6, and 2. How many data values are there in all?

Add all the frequencies together. Check your answer in the back of this chapter.

Practice

Mastered 0 of 11

Warm-up

Ease in with the basics.

  1. 1.A histogram has frequencies 4, 6, and 5. How many data values are there in all?

  2. 2.Which graph groups numerical data into equal intervals: a histogram or a bar graph?

  3. 3.An interval 20 to 29 has a frequency of 7. What does the 7 mean?

On Level

The core Quick Check from the book.

  1. 1.A histogram shows frequencies 3, 5, and 7. How many data values in all?

  2. 2.Which graph groups numerical data into equal intervals: a histogram or a bar graph?

  3. 3.An interval 10 to 19 has a frequency of 6. What does 6 mean here?

  4. 4.Frequencies are 2, 9, and 4. Which interval has the fewest values?

  5. 5.Should a histogram have equal or unequal intervals?

Challenge

Stretch your thinking.

  1. 1.A histogram has intervals 0 to 9, 10 to 19, 20 to 29, and 30 to 39 with frequencies 3, 8, 6, and 3. How many values are 20 or greater?

  2. 2.A histogram of test scores has frequencies 2, 5, 9, and 4 for four equal intervals. Which interval has the most values, and how many students took the test in all?

  3. 3.Why must a histogram use equal-width intervals?