Graphs & Charts
LINE GRAPHS 1
Line graphs are mainly used to show things changing over time.
The horizontal axis
usually shows the time: hours, years etc.
The vertical axis shows the changes.
On both axes, the scale goes up in equal steps.
1)
This graph shows the growth of a pine tree.
What does the horizontal axis show?
What does the vertical axis show?
What does each step represent on the horizontal axis?
What does each step represent on the vertical axis?
15
Year
10
5
0
1968
1972
1976
1980
1984
1988
H e ig h t in m e tre s
Adapted from Liverpool College Press
Line graphs
Level 1
1992
1996
2000
Graphs & Charts
How high was the tree in 1980?
Follow the dotted line up from 1980. Where it meets the line graph,
follow it across to find the height. Check the scale again - it goes up in
1’s, so the height was 7 metres.
When did the tree reach 10 metres?
Find ten metres on the vertical axis. Follow it across to the graph
(draw a line if you like), then turn down to find which year - 1992.
Try these questions:
(a) How high was the tree in 1988?
(b) How high was the tree in 1984?
(c) How high was the tree in 1998? (check the scale along)
(d) How high was it in 1974?
(e) When did it reach 3 metres?
(f) When did it reach 6 metres?
(g) When do you think the tree was growing most quickly?
Either up to 1980
or 1980 to 1992?
To Complete a Line Graph
Check the scale of the graph - what does each step stand for?
Plot each of the points with a small cross or dot and join the points
using a ruler.
Adapted from Liverpool College Press
Line graphs
Level 1
Graphs & Charts
2)
UK MUSIC SALES
This graph shows how many cassette tapes have been sold in the UK.
160
140
M illio n s o f s a le s
120
100
80
60
40
20
0
1972
74
76
78
80
82
84
86
88
90
92
94
96
98
(a) When were cassettes first sold?
(b) In which year were 40 million sold?
(c) During which 2 year period did sales go up most?
(d) When were the most cassettes sold ever? How many?
(e) During which years did sales fall?
The table below shows sales of CD’s during this time, in millions
1984
1986
1988
1990
1992
1994
1996
1998
0
10
30
50
70
100
140
150
Adapted from Liverpool College Press
Line graphs
Level 1
2000
Graphs & Charts
(f) Between which years did sales of CD’s first begin?
(g) Use the axes above to plot CD sales and draw a line graph.
Estimate the answers to these questions:
(h) When did CD sales reach 40 million?
(i) In which year did sales of CD’s overtake sales of
cassettes?
(j) When did CD sales rise most steeply?
(k) When did they begin to level off?
Adapted from Liverpool College Press
Line graphs
Level 1
Graphs & Charts
3) ELECTRIC KETTLE’S HEATING SPEED
The following graph shows the time taken for water to boil in an
electric kettle.
Check the scale on both axes then answer the questions.
100
90
80
Te m p e ra tu re ° C
70
60
50
40
30
20
10
0
0
0 .5
1
1 .5
2
2 .5
3
3 .5
4
T im e in m in u te s a fte r s w itc h in g o n
What was the temperature of the water:
(a) when the kettle was switched on?
(b) after 1 minute?
(c) after 2 minutes?
(d) after 3 minutes?
How long did it take the water to reach a temperature of:
(e) 15°C
(f) 65°C
(g) 95°C
Adapted from Liverpool College Press
Line graphs
Level 1
Graphs & Charts
(h) Between which times did the water heat most quickly?
(i) How long did it take the water to boil?
Answers
1)
Time in years
Height in metres
horizontal axis - 1 step = 1
year
vertical axis 1 step = 1
metre
(a) 9 metres
2)
3)
(c) 11 metres
(d) 4 metres
(e) 1972
(f) 1978
(b) 8 metres
(g) up to 1980 (the line is
steeper)
(a) 1972
(f) 1984-1986
(b) 1984
(h) 1989
(c) 1984-1986
(i) 1991-2
(d) 1988 - 80 million
(j) 1994-96
(e) 1988-1994
(k) 1996-98
(a) 10°
(b) 15°
(c) 20°
(d) 80°
(e) 1 minute
(f) 2.5 minutes (2 12 )
(g) 3.5 minutes (3 12 )
(h) 2 minutes - 2.5 minutes
(i) 4 minutes to reach 100°
Adapted from Liverpool College Press
Line graphs
Level 1