Page 138 - MAT KS3 Y8 Cambridge CheckPoint

13.4 Graphs in real-life contexts

13.4 Graphs in real-life contexts

Graphs give information in a visual form. Therefore, they Real-life graphs usually only have positive
are often used in real-life contexts because they can be axes. They may not start at zero.
easier to interpret than a table or chart.

The numbers on the axes can represent almost anything. You will usually see a different variable on
each axis. Often, one of the axes will show time.

Read any labels on the axes and look at the scale carefully to see what the intervals on each axis
stand for.

Worked example 13.4

This graph shows fares charged by two different taxis. 16 Taxi A
a How much does each taxi charge for a journey of 7 km?
14
b How much does taxi A charge for each kilometre? Taxi B
12
c Taxi B has a fixed charge and then charges a certain 10
amount for each kilometre. Cost ($)
i How much is the fixed charge? 8
ii How much is each kilometre? 6
d What distance will cost the same amount in either taxi? 4
2
0
0 1 2 3 4 5 6 7 8 9 10
Distance (km)

a A charges $14, B charges $11. Find the cost coordinate when the distance coordinate is 7.
b $2 1 km costs $2, 2 km costs $4, and so on.
c i $4 If the distance is 0, the charge is $4.
ii $1 1 km costs $5, 2 km costs $6, 3 km costs $7. One extra dollar for each extra
kilometre.
d 4 km This is the point where the two lines cross.

✦ Exercise 13.4

1 Zalika and Tanesha are cycling on the same route.
35
The graph shows their journeys. 30
a Zalika started at 09 00. What time did Tanesha start? 25
b How far did Zalika travel in the first hour? Distance (km) 20 Zalika
c How long was Tanesha cycling before she caught 15 Tanesha
up with Zalika? 10
5
0
0900 0930 1000 1030

Time (24-hour clock)

136 13 Graphs