Page 149 - Mathematics Coursebook

15.3 Real-life graphs

15.3 Real-life graphs y

Graphs can tell stories. 2.0
!is graph shows Ari’s journey from home. 1.5
First look at the two axes. Distance from home (km) 1.0
!e horizontal axis shows time (in minutes).
!e vertical axis shows Ari’s distance from home (in kilometres). 0.5
!e graph is in three parts. 0 x
0 10 20 30 40
t He walks for 10 minutes and travels 1 km. Time (minutes)
t He waits for a bus for 20 minutes. You can tell he is not moving
because the line is horizontal.
t !e bus does not come. He starts walking again. A$er a total of
40 minutes he is 1.5 km from home.
In the %rst part, Ari took 5 minutes to walk 0.5 km. In the third part he took 15 minutes to walk 0.5 km.
He walked more slowly in the third part. You can see this on the graph. When the graph is steeper (%rst
part) he is walking faster. When the graph is less steep (third part) he is walking more slowly.

) Exercise 15.3

1 This graph shows a car journey. y
The journey was in two stages with a rest break.
a Work out the time taken for the first part of the journey. 200
b Work out the distance the car travelled in the first part. 150
c Work out the time taken for the rest break.
d Work out the time taken for the whole journey. Distance from start (km) 100
e Work out the total distance travelled.
f Did the car travel more quickly in the first stage 50
or the last stage? Give a reason for your answer.
0
0 1 2 3 4 x
Time (hours)

2 Luis drove to Overton. y
He stayed there for a while and then he drove back
home. The graph shows his journey. 200
a Work out the distance from Luis’s home to Overton.
b Work out how long Luis was at Overton. Distance from start (km) 150
c Find: i the time taken to reach Overton 100
ii the time taken to get back home from
Overton. 50
d Did Luis drive faster travelling to Overton or going
home? 0 0 1 2 3 4 5 6 x
Time (hours)

148 15 Time