New
New
Year 8

Interpreting pie charts

I can interpret pie charts.

New
New
Year 8

Interpreting pie charts

I can interpret pie charts.

Lesson details

Key learning points

  1. Knowing the angle size for a sector allows calculation of the frequency.
  2. By knowing the total, statements can be made comparing the data.
  3. Different pie charts may have different totals even though proportions are the same.

Keywords

  • Pie chart - A pie chart (pie graph) is a circular graph where sectors represent different groups proportionally.

  • Frequency - The frequency is the number of times an event occurs; or the number of individuals (people, animals etc.) with some specific property.

  • Sector - A sector is the region formed between two radii and their connecting arc.

  • Proportion - Proportion is a part to whole (sometimes part to part) comparison. If two things are proportional, the ratio of part to whole is maintained

  • Degrees - Degrees are the most common unit of measurement for angle. One whole turn is equal to 360 degrees, written 360°.

Common misconception

Two sectors on two different pie charts that have the same angle represent the same frequency.

90° of a pie chart of 4 data points represents less frequency (frequency of 1) than 90° of a pie chart of 200 data points (frequency of 50).

Pie charts represent proportion, not frequency. This is shown through first comparing two pie charts which represent vastly different frequencies: one large, one small. Is three quarters of a small dataset larger than one quarter of a large dataset?
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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6 Questions

Q1.
120 people were asked: "what do you most frequently drink whilst at work". The results will be placed in a pie chart with a total of 20 pre-defined sectors. How many sectors would represent water?
An image in a quiz
3.6
6
Correct answer: 12
72
360
Q2.
120 people were asked: "what do you most frequently drink whilst at work". The results will be placed in a pie chart with a total of 20 pre-defined sectors. How many people voted for milk?
An image in a quiz
Correct Answer: 24, 24 people, 24people
Q3.
A large set of information is collected and represented in a pie chart of 30 equally-sized sectors. Each sector represents a frequency of 40. What is the total frequency of this dataset?
Correct Answer: 1200
Q4.
Which of these words is not an essential feature of a pie chart or the calculations required to construct a pie chart?
radius
sector
Correct answer: linear
frequency / value
Correct answer: pi ($$\pi$$)
Q5.
The incomplete ratio table shows a dataset being converted into angles to represent each subgroup as sectors on a pie chart. Match the letters to the correct missing values.
An image in a quiz
Correct Answer:a,120

120

Correct Answer:b,360

360

Correct Answer:c,3

3

Correct Answer:d,54

54

Correct Answer:e,132

132

Q6.
The incomplete ratio table shows a dataset being converted into angles to represent each subgroup as sectors on a pie chart. Find the value of angle a, in degrees.
An image in a quiz
Correct Answer: 160, 160 degrees, 160degrees

6 Questions

Q1.
The table shows the number of people at Location 1 and their preferred cooking style for potatoes. By choosing an appropriate row to perform calculations on, find the value of the unknown multiplier.
An image in a quiz
40
9
Correct answer: 3
13
39
Q2.
The table shows the number of people at Location 2 and their preferred cooking style for potatoes. Find the multiplier linking frequency and angle.
An image in a quiz
Correct Answer: 2, x2, *2
Q3.
Find the number of people who preferred boiled potatoes.
An image in a quiz
Correct Answer: 36, 36 people, 36people
Q4.
Match the missing number (labelled by a letter) in the ratio table with its correct value.
An image in a quiz
Correct Answer:a,4

4

Correct Answer:b,128

128

Correct Answer:c,72

72

Correct Answer:d,18

18

Correct Answer:e,90

90

Q5.
Below are correctly drawn pie charts showing the preferred cooking methods for potatoes for people at Locations 4 and 5. Select the statements that are always true.
An image in a quiz
The same number of people (25 people) voted for boiled at both Locations 4 and 5
Correct answer: The same percentage of people (25%) voted for boiled at both Locations 4 and 5
A greater number of people voted for roasted in Location 5 than Location 4
Correct answer: A greater proportion of people voted for roasted in Location 5 than Location 4
The same number of people voted in Locations 4 and 5
Q6.
75 people voted for roasted in Location 4. By using a protractor and this information, calculate the total frequency of the people who voted in Location 4.
An image in a quiz
Correct Answer: 200, 200 people, 200people