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This pdf shows that the Line graphs are another visual way of presenting data. Often they are used to show how a value changes over time.

1.
Line Graphs

Line graphs are another visual way of presenting data.

Often they are used to show how a value changes over

This line graphs shows how Total Sales (£000s)

total sales for a company 30

TOTAL SALES (£000S)

have changed over five 25

28

20 25

years. 21

23

15 19

(i) What was the best 10

5

year for sales in the

0

2010 - 2014 period? 2010 2011 2012 2013 2014

YEAR

The best year for sales is

where the line reaches its

peak, 2013.

(ii) In 2012, online sales comprised 45% of total sales. What was the

value of online sales in 2012?

From the line graph, we can see that the value for total sales for 2012 is 25.

We need to calculate 45% of 25 45% x 25 = 11.25

We remember that the unit here is thousands of pounds (£000s), so the

answer is that online sales had a value of £11,250 in 2012.

(iii) What was the percentage increase in total sales between 2010 and

2014, to one decimal place?

Total sales increased from 19 in 2010 to 23 in 2014. (We note that it is easier to

leave the values as they are, rather than translate them to £000s – this is valid

as we are comparing ‘like with like’ in these calculations). Therefore, there

was an increase in total sales of 23 – 19 = 4

We need to calculate this increase as a percentage of the 2010 figure

4 / 19 x 100 = 21.05%. Since we have been asked to calculate the value to

one decimal place, the correct answer is 21.1%.

Author Dr Eleanor Lingham

De Montfort University

Moderator Dr Julie Crowley

Cork Institute of Technology

Line graphs are another visual way of presenting data.

Often they are used to show how a value changes over

This line graphs shows how Total Sales (£000s)

total sales for a company 30

TOTAL SALES (£000S)

have changed over five 25

28

20 25

years. 21

23

15 19

(i) What was the best 10

5

year for sales in the

0

2010 - 2014 period? 2010 2011 2012 2013 2014

YEAR

The best year for sales is

where the line reaches its

peak, 2013.

(ii) In 2012, online sales comprised 45% of total sales. What was the

value of online sales in 2012?

From the line graph, we can see that the value for total sales for 2012 is 25.

We need to calculate 45% of 25 45% x 25 = 11.25

We remember that the unit here is thousands of pounds (£000s), so the

answer is that online sales had a value of £11,250 in 2012.

(iii) What was the percentage increase in total sales between 2010 and

2014, to one decimal place?

Total sales increased from 19 in 2010 to 23 in 2014. (We note that it is easier to

leave the values as they are, rather than translate them to £000s – this is valid

as we are comparing ‘like with like’ in these calculations). Therefore, there

was an increase in total sales of 23 – 19 = 4

We need to calculate this increase as a percentage of the 2010 figure

4 / 19 x 100 = 21.05%. Since we have been asked to calculate the value to

one decimal place, the correct answer is 21.1%.

Author Dr Eleanor Lingham

De Montfort University

Moderator Dr Julie Crowley

Cork Institute of Technology

2.
Line graphs can also be used to show how two or more

values change over time.

This line graph shows share

price changes to two Share Price

companies over a four

£9.00

year period. £8.50

£8.00

(i) What is the

SHARE PRICE

£7.50

difference £7.00

ABC Ltd

between the £6.50

DEF Plc

ABC Ltd share £6.00

£5.50

price and the

£5.00

DEF Plc share 2012 2013 2014 2015

price in 2012? YEAR

The difference between

the share prices in 2012 is 8.20 – 7.50 = 0.70

There is a difference of £0.70 between the ABC Ltd share price and the DEF

Plc share price in 2012.

(ii) In which year was the largest percentage increase in share price for

ABC Ltd?

From the line graph, we can see that the ABC Ltd share price increased in

2014 and 2015. We need the calculate the increase in price in each year

2014 6.50 – 6.00 = 0.50

2015 6.70 – 6.50 = 0.20

We then calculate each as a percentage the Speed Tip!

share price in the earlier year

From the graph, you

0.50 / 6.00 x 100 = 8.33%

could guess the

0.20 / 6.50 x 100 = 3.07%

answer for (ii).

Therefore the largest percentage increase in

share price was in 2014.

Author Dr Eleanor Lingham

De Montfort University

Moderator Dr Julie Crowley

Cork Institute of Technology

values change over time.

This line graph shows share

price changes to two Share Price

companies over a four

£9.00

year period. £8.50

£8.00

(i) What is the

SHARE PRICE

£7.50

difference £7.00

ABC Ltd

between the £6.50

DEF Plc

ABC Ltd share £6.00

£5.50

price and the

£5.00

DEF Plc share 2012 2013 2014 2015

price in 2012? YEAR

The difference between

the share prices in 2012 is 8.20 – 7.50 = 0.70

There is a difference of £0.70 between the ABC Ltd share price and the DEF

Plc share price in 2012.

(ii) In which year was the largest percentage increase in share price for

ABC Ltd?

From the line graph, we can see that the ABC Ltd share price increased in

2014 and 2015. We need the calculate the increase in price in each year

2014 6.50 – 6.00 = 0.50

2015 6.70 – 6.50 = 0.20

We then calculate each as a percentage the Speed Tip!

share price in the earlier year

From the graph, you

0.50 / 6.00 x 100 = 8.33%

could guess the

0.20 / 6.50 x 100 = 3.07%

answer for (ii).

Therefore the largest percentage increase in

share price was in 2014.

Author Dr Eleanor Lingham

De Montfort University

Moderator Dr Julie Crowley

Cork Institute of Technology