# Unit 20 Section 2 : Data display

In this section we revise how to display data visually using bar charts, vertical line diagrams, pie charts and pictograms.

## Examples

Example 1: Pie Chart
At the end of each half term, the students in a particular school are graded A, B or C for their reports.
The table below shows the grades awarded for one class. Illustrate this data using a pie chart.

First we need to find out how many items of data there are: 12 + 16 + 2 = 30
Next we need to work out the angle for one item of data: 360° ÷ 30 = 12°
Now we can find the correct angles for each category, by multiplying the frequency by 12°: Once we have the angles, and have checked that they add up to 360°, we can plot the pie chart.
We plot the categories in the order they appear in the table, turning clockwise from a vertical line above the centre:

Example 2: Pictogram and Bar Chart
A school canteen offers students a choice of burgers, sandwiches, baked potatoes or the meal of the day.
On one day the number of children making each choice was recorded; the table below shows the children's choices: Illustrate this data using (a) a pictogram, and (b) a bar chart.

(a) Pictogram
We will use the symbol to represent 20 people, which means that the symbol will represent 10 people. (b) Bar Chart
This is very similar to the pictogram, except vertical rectangular bars are used instead of lines of symbols.

Example 3: Vertical Line Diagram
The pupils in class 7C were given a short maths test. The scores are listed in the following table: Illustrate these results on a vertical line diagram.

## Exercises

Work out the answers to the questions below and fill in the boxes. Click on the button to find out whether you have answered correctly. If you are right then will appear and you should move on to the next question. If appears then your answer is wrong. Click on to clear your original answer and have another go. If you can't work out the right answer then click on to see the answer.

Question 1
Ameer visits a car park and records the registration letter of each of the cars there.
The results are given in the table below: Ameer wants to produce a pie chart.

(a) What angle will be used to represent one car?
°

(b) Complete the following table to show the angles which Ameer must plot in his pie chart:
 Letter Frequency Angle in pie chart P 3 ° R 6 ° S 7 ° T 2 ° V 5 ° W 3 ° Other 10 °

 In some of these questions you will need to draw lines, bars or rows of symbols on a vertical line diagram, bar chart or pictogram. To do so, click on the grid where you want the line to finish. If you want to change the position, click at a different position in the same row or column. If you want to remove a line, bar or row of symbols, click the highest part of the line. Practise this on the vertical line diagram in Question 2.

Question 2
Pupils in class 8B record the number of bus journeys made by each member of their class during one week.
The results are listed in the following table:

Illustrate this data using a vertical line diagram.

Question 3
A survey was carried out to see how children in a school rated their school bus service.
The results are listed in the following table:

Illustrate these results with a pictogram. Use to represent 2 pupils.

Question 4
Mandy draws the bar chart below to illustrate the ages of some of her friends:
 (a) How many of Mandy's friends are included on the bar chart? (b) Mandy is 13. How many of her friends are the same age? (c) How many of her friends are aged 14 or younger?
Question 5
A class carried out a survey to find out how many TV sets there were in each of their homes.
The results are shown in the following table:

Illustrate this data using a bar chart.

Question 6
Jason has £3 per week pocket money. One week, Jason spent his £3 pocket money on the following items: Jason wants to produce a pie chart to show how he spent his pocket money.

(a) In total Jason had £3, which is 300p. What angle will be used for 1p?
°

(b) Complete the table below to show the angles Jason should draw in his pie chart:
 Item Amount spent Angle in pie chart Sweets 60p ° Football club 100p ° Tennis club 50p ° Comics 70p ° New pencil 20p °

Question 7
The pupils in a class carry out a survey to determine their favourite types of television programme.
The results are given in the following table:
Illustrate this data using a bar chart.

Question 8
A pocket money survey for a group of 50 students produced the following results:

(a) Illustrate this data using a bar chart.

(b) Sam gets £4 pocket money each week. Would Sam be wise to use the results
of this survey to support his request for an increase in his pocket money?

You have now completed Unit 20 Section 2
 Your overall score for this section is Correct Answers You answered questions correctly out of the questions in this section. Incorrect Answers There were questions where you used the Tell Me button. There were questions with wrong answers. There were questions you didn't attempt.
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Produced by A.J. Reynolds August 2008