Page 182 - Mathematics Coursebook

19.1 Interpreting and drawing pictograms, bar charts, bar-line graphs and frequency diagrams

I
19.1 nterpreting and drawing pictograms, bar charts, bar-line graphs
and frequency diagrams

In a pictogram, you use pictures to represent data. You can use each picture to represent an item or a
number of items. #e key shows how many items one picture represents. When you draw a pictogram you

must make sure that:
t the pictures are all the same size
t the pictures are in line horizontally and vertically
t you include a key.

Worked example 19.1A
The pictogram shows the number of hours of sunshine on 1 July in Cape Town
three cities. Manama
a Which city had the least sunshine? New York
b How many hours of sunshine were there in:
i New York ii Manama? Key: represents 2 hours of sunshine

a Cape Town Cape Town has the fewest pictures, so has the least amount of sunshine.
b i 4 × 2 = 8 hours New York has 4 pictures. The key tells you that 1 picture represents 2 hours.
So New York has 8 hours of sunshine.
1
ii 5 × 2 = 10 hours Manama has 5 pictures. 5 pictures represent 10 hours.
2
1
5 × 2 = 1 hour Half a picture represents 1 hour.
2
10 + 1 = 11 hours Add 10 and 1 to work out the total number of hours.

In a bar chart, you use bars to show data. When you draw a bar chart you must make sure that:
t the bars are all the same width and the gap between bars is always the same
t each bar has a label underneath it
t the bar chart has a title and the axes are labelled
t you use a sensible scale on the vertical axis.

Worked example 19.1B

The table shows the favourite fruit of the students in Mrs Hassan’s class.
Fruit apple pear orange banana
Number of students 7 6 4 8

Draw a bar chart to show this information.

Favourite fruit You can see that the bars are the same width and gaps
between the bars are equal. Each bar has a label underneath
Number of students 7 the axes are labelled ‘Fruit’ and ‘Number of students’. The
9
to show which fruit it represents. The chart has a title and
8
scale on the vertical axis is ‘1 division represents 1 student’.
6
Each bar is drawn to the correct height to represent the
5
4
number of students who chose that fruit.
3
2
1
0
Apple Pear Orange Banana
Fruit
19 Interpreting and discussing results 181