3
8
The table shows the price of nails at a DIY
The table shows the amount paid for
store.
different size containers of milk.
Number of litres, n 0.6
Mass of nails (kg)
0.5
1
2
5
1
1.2
2
2.4
Price of nails (£)
Cost, C (p)
1.20 2.40 4.80
12
48 80 96 160 192
a
Plot a line graph for these values.
a
Draw the graph.
b
Is the price of the nails in direct proportion
b
Work out the equation of the line.
to the mass? Explain your answer.
Are C and n in direct proportion?
c
d
Write a formula linking the number of
4
This line graph shows the price of petrol by
litres (n) and the cost (C ) .
volume.
e
Use the formula to work out the cost of
Price of petrol
3.6 litres of milk.
8
9
Look back at the graph in Q1.
6
a
Write the ratio kilograms : pounds in its
4
simplest form.
b
2
Work out the gradient of the graph.
Write a formula that links kilograms (K)
c
0
0 1 2 3 4 5
and pounds (P) .
Litres
10
On a particular day, the ratio of GB pounds to
a
Are price and volume in direct proportion?
US dollars is 5 : 9.
b
Work out the gradient of the line.
a
Copy and complete this table of values for
c
How much does 1 litre of petrol cost?
pounds and dollars.
5
R
Which of these are in direct proportion?
GB pounds (£)
0
5
10
Give reasons for your answers.
a
Miles and kilometres
US dollars ($)
b
Age and number of pets
b
Draw a conversion graph for pounds to
c
Litres and millilitres
dollars.
d
Number of people at a bus stop and time
c
Write 5 : 9 as a unit ratio.
of day
Write a formula linking dollars ( y) and
d
6
P
An electrician charges a callout fee of £35
pounds (x).
plus £42 per hour she works.
11
Exam-style question
Is her total charge (C ) in direct proportion to
the number of hours (h) she works?
P A plumber uses a formula to work out the
cost (C) of a job according to the number of
7
Which of these sketch graphs show one
hours (H) it takes. His formula is
variable in direct proportion to the other?
C = 35H + 45
A
B
C
Is the plumber’s charge for a job in direct
proportion to the amount of time it takes?
(2 marks)
Explain your answer.
O
O
O
Exam hint
D
E
You won’t get any marks for just ‘Yes’ or ‘No’.
You must write ‘Yes’ or ‘No’ because ………….
O
O
91
11.7 Proportion and graphs
R = Reasoning P = Problem-solving