Chapter
12
Measurement
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Contents:
A Length
B Perimeter
C Area
D The area of a rectangle
E Other areas
F Volume
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MEASUREMENT
(Chapter 12)
Opening problem
Peter is building a raised garden bed for his son’s primary school. Its sides will be made of
wood, and it will be 4 m long, 1:2 m wide, and 0:3 m high.
Things to think about:
a What length of 0:3 m wide wood is
needed to make the walls or perimeter of
the garden bed?
b What area of weed mat is needed to cover
the base of the garden bed?
c What volume of soil is needed to fill the
garden bed?
0.3 m
1.2 m
4m
Builders, engineers, architects, landscapers, and surveyors all rely on accurate measurements to
carry out their jobs. In this chapter we will look at measurements of length, area, and volume.
LENGTH
A
A length is a measure of distance.
Lengths are used to express how far one object is from another. For example:
“I live 5 kilometres from school.”
“He takes the mark 40 metres from goal.”
“Rule a margin 2 centimetres from the edge of the page.”
The metre is the base unit for length in the metric system.
Other commonly used units of length based on the metre are
the kilometre, centimetre, and millimetre.
1
2
1 km is 2 times around an athletics track.
1 kilometre (km) = 1000 metres (m)
1 metre (m) = 100 centimetres (cm)
1 m is about the length of an adult’s stride.
1 centimetre (cm) = 10 millimetres (mm)
1 cm is about the width of a fingernail.
Estimating lengths and using appropriate units
to describe them are important skills.
10 mm
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Discussion
Why do we use different units to measure lengths?
Why don’t we just use metres to measure all lengths?
LENGTH CONVERSIONS
When we convert from one unit to a smaller unit, there will be more smaller units. We therefore
need to multiply.
When we convert from one unit to a larger unit, there will be less larger units. We therefore need
to divide.
´100
´1000
cm
m
km
´10
¸1000
¸100
mm
¸10
Example 1
Self Tutor
Write the following in metres:
a 640 cm
b 3:8 km
c 7560 mm
a We are converting
from a smaller unit
to a larger one, so
we divide.
640 cm
= (640 ¥ 100) m
= 6:4 m
b We are converting
from a larger unit to
a smaller one, so we
multiply.
c We are converting
from a smaller unit
to a larger one, so
we divide.
7560 mm
= (7560 ¥ 1000) m
= 7:56 m
3:8 km
= (3:8 £ 1000) m
= 3800 m
EXERCISE 12A
1 What unit would you use to measure:
a the length of a necklace
b the length of a major highway
c the wingspan of a 747 jet
d the length of a tennis court
e the thickness of a DVD
f the width of a mobile phone?
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2 Choose the correct answer.
a The length of a fly would be:
A 7 cm
B 7 mm
C 7m
b The flight distance from Broome to Townsville would be:
A 25 900 m
B 259 cm
C 25:9 mm
c The width of a public swimming pool would be:
A 20 000 cm
B 200 cm
C 2000 cm
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D 7 km
D 2590 km
D 20 km
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3 Write in metres:
a 760 cm
e 2763 mm
b 400 mm
f 25 000 cm
c 2 km
g 4:7 km
d 25 cm
h 0:09 km
4 Write in centimetres:
a 550 m
e 1377 mm
b 47 mm
f 8:7 km
c 1:3 m
g 290 m
d 435 mm
h 1:96 km
5 Write in mm:
a 2:5 cm
b 1:83 m
c 49 cm
d 0:92 m
6 Write in km:
a 3371 m
b 21 901 m
c 267 000 cm
d 38 800 cm
7 Use a ruler to find the total length of each line. Give your answer in:
i centimetres
ii millimetres.
a
b
c
d
8 Convert all lengths to metres and then add:
a 17 m + 81 cm + 262 mm
c 4 km + 220 m + 16 cm
e 60 km + 93 m + 93 cm + 7 mm
b 264 m + 308 cm + 21 mm
d 12 km + 724 m + 56 cm + 88 mm
f 29 km + 39 m + 920 cm + 888 mm
9 Write each set of distances in the same units, and hence write them in ascending order:
a
c
e
g
22 mm, 2 cm
650 cm, 7 m, 6800 mm
2700 mm, 2:75 m, 247 cm
5:66 m, 560 cm, 5650 mm
4250 m, 4:26 km
0:003 km, 382 cm, 3:8 m
0:334 km, 344 m, 34 000 cm
8:2 m, 8150 cm, 81 800 mm
b
d
f
h
PERIMETER
B
The perimeter of a closed figure is a measurement of
the distance around the boundary of the figure.
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The word
perimeter is also
used to describe
the boundary of a
closed figure.
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A polygon is a closed figure with straight sides. Its
perimeter is found by adding the lengths of the sides.
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(Chapter 12)
We can write rules for the perimeter P of very common simple shapes.
Triangle
Square
Rectangle
b
a
s
w
c
l
P =a+b+c
P =4£s
P = (l + w) £ 2
P = 4 £ side length
P = (length + width) £ 2
In figures, sides
having the same
markings show
equal lengths.
Example 2
Self Tutor
a
Find the perimeter of:
b
7 cm
8 cm
3 cm
9 cm
17 cm
a Perimeter = 3 + 7 + 9 cm
= 19 cm
b P = (17 + 8) £ 2 cm
= 25 £ 2 cm
= 50 cm
EXERCISE 12B
1 Find the perimeter of each triangle:
a
b
21 mm
c
26 km
27 mm
3.6 km
10 km
38 mm
24 km
1.1 km
d
e
f
9.8 m
14 m
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(Chapter 12)
2 Find the perimeter of each figure:
a
b
2.7 m
5 cm
1.7 m
c
d
4.5 km
121 mm
18.1 km
e
Use the
correct units!
f
4.1 km
15 mm
35 mm
3 Find the perimeter of each figure:
a
b
3m
c
10 mm
10 m
8m
8 mm
14 m
9 cm
6m
d
e
f
4.9 km
56 mm
3.2 km
65 mm
2.4 cm
80 mm
4 Estimate the perimeter of each figure, then check your estimate with a ruler.
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5 Use a piece of string to estimate, as accurately as possible, the perimeter of:
a
b
c
6 A triangular car yard with sides 470 m, 320 m, and
280 m is to be fenced. Find the length of the fence.
7 How far will a cyclist ride if she completes 7 laps
of a 150 m by 220 m rectangular block?
8 A rectangular section of road 10 m long and 3:2 m
wide must be surrounded by bunting so roadworks
can be done. What length of bunting is required?
Draw diagrams
to help solve
these problems.
Activity 1
Step estimation
Some of us are short and others are tall. When we walk, our
step lengths vary from one person to another.
By knowing your step length, you can estimate long distances
with reasonable accuracy.
Seani set up two flags which she measured to be 100 metres
apart. Using her usual walking step, she took 128
1
steps to
2
walk between them.
100 m ¥ 128:5 is about 0:78 m, so Seani’s usual step length
is about 0:78 m.
When Seani walked around the school’s boundary, she took 2186 steps.
Since 2186 £ 0:78 ¼ 1705, she estimated the school’s perimeter to be 1705 metres.
What to do:
1 Use a long tape measure to help place two flags exactly 100 metres apart.
2 Walk with your usual step from one flag to the other. Count the steps you take.
3 Using Seani’s method, calculate your usual step length correct to 2 decimal places.
4 Choose three suitable distances around the school to estimate. Use Seani’s method to
estimate them.
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5 Compare your estimates with other students. You could organise a competition to find the
best distance estimator in your class.
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MEASUREMENT
(Chapter 12)
C
AREA
In any house or apartment there are surfaces such as carpets, walls, ceilings, and shelves. These
surfaces have boundaries which define the shape of the surface.
People often need to measure the amount of surface within a boundary. The surface may be land,
a wall, or an amount of dress material.
Area is the amount of surface inside a region.
Descriptions on cans of paint, insect surface spray, and bags of fertiliser refer to the area they can
cover. Garden sprinklers are designed to spray water over a particular area.
Investigation 1
Choosing units of area
Some identical shapes can be placed together to cover a surface with no gaps.
For example:
squares
equilateral triangles
regular hexagons
We can use these shapes to compare different areas.
What to do:
1 Compare the areas of these shapes. For each pair, which has the bigger area?
a
A
B
b
A
B
2 Use 4 as a unit of area to measure the area of each of the shapes:
a
c
b
d
3 Explain why a circle would be an inappropriate choice as a unit of area.
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4 Suppose you wish to compare the areas of
the two illustrated rectangles.
Which of the shapes above would be best
to use as a measure of area? Explain your
answer.
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261
SQUARE UNITS
As you have seen, it is possible to compare area using
a variety of shapes. Some shapes have advantages
over others.
5
12
5 * 12 = 60 squares
The square has been chosen as the universal unit used
to measure area.
The area of a closed figure, no matter what shape, is the
number of square units (units2 or u2 ) it encloses.
EXERCISE 12C.1
1 Find the area in square units of each of the following shapes:
2
a
b
c
d
e
f
a Find the perimeter of each figure:
i
ii
iv
iii
v
vi
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b Check to see that all of the above shapes have the same area. What is this area?
c What do your answers in a and b tell you about the area and perimeter of a shape?
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MEASUREMENT
(Chapter 12)
1 mm 2
METRIC AREA UNITS
1 cm 2
In the metric system, the units of measurement used for area
are related to the units we use for length.
1 square millimetre (mm2 ) is the area enclosed by a square of side length 1 mm.
1 square centimetre (cm2 ) is the area enclosed by a square of side length 1 cm.
1 square metre (m2 ) is the area enclosed by a square of side length 1 m.
1 square kilometre (km2 ) is the area enclosed by a square of side length 1 km.
EXERCISE 12C.2
1 What units of area would most sensibly be used to measure the areas of the following?
a the top of a cake
b a suburb in Sydney
c a large rug
d a fingernail
e a table top
f a drink coaster
g a school oval
h a page of a magazine
i Tasmania
j a paver
2 Christine is tiling her kitchen walls
according to the diagram.
a How many tiles have been used?
b There are 20 tiles for each square
metre. How many square metres
of tiles were used?
c The tiles cost $44:00 per square
metre, and it cost $19:00 per
square metre to install them.
What is the total cost of the tiling
job?
3
a In the given picture, how many pavers
were used for:
i the driveway
ii the patio?
b The pavers in the patio are the same as
the pavers in the driveway. If there are 50
pavers in every square metre, how many
square metres of paving were laid?
10 rows of
28 pavers
c If the cost of the pavers is $16:90 per m2 ,
and the cost of laying them is $14 per m2 ,
what is the total cost of the paving?
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(Chapter 12)
263
THE AREA OF A RECTANGLE
D
Consider a rectangle 5 units long and 3 units wide.
DEMO
5 units
Clearly the area of this rectangle is 15 units2 , and
we can find this by multiplying 5 £ 3 = 15.
3 units
This leads to the general rule:
Area of rectangle = length £ width
A=l£w
width w
length l
Since a square is a rectangle with equal length
and width:
A = length £ length
=l£l
= l2
l
square
l
Example 3
Self Tutor
Find the areas of the following rectangles:
a
b
5 cm
4.2 m
16.3 m
8 cm
a Area = length £ width
= 8 cm £ 5 cm
= 40 cm2
b Area = length £ width
= 16:3 m £ 4:2 m
= 68:46 m2
EXERCISE 12D
1 Find the area of the following:
a
b
c
25 mm
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14 km
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MEASUREMENT
(Chapter 12)
d
e
f
13 km
9.1 cm
200 m
3 km
g
h
i
2.7 cm
30 cm
40 cm
10.5 m
8.5 m
1.5 cm
2 Tom wants to cover his 13 m by 12 m backyard with lawn. Seed for the lawn costs $7:50 per
square metre.
a Find the area of the lawn.
b Find the total cost of the seed for the lawn.
3 A 5 m by 7 m room has a 2 m by 3 m rug on the floor. Find the area of exposed floor.
4 A ceiling 6 m by 7:5 m is to be painted. One litre of paint covers 15 square metres.
a Find the area to be painted.
b What is the total amount of paint required for the ceiling?
5 A hallway 1:8 m by 9 m is to be covered in floorboards
15 cm by 1:5 m.
Each floorboard costs $21:50.
a Find the area, in square metres, of each floorboard.
b Find the area of the floor.
c Find the number of floorboards required.
d Find the total cost of the floorboards.
To use the formula
A = l £ w, each
length must be in
the same units.
Activity 2
Working with area
What to do:
1 Draw a square metre with chalk.
Estimate how many members of your class can stand on the square metre with feet entirely
within it. Check your estimate.
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2 Use a measuring tape to measure the dimensions of some rectangular regions, such as the
floor area of a classroom, a tennis court, a basketball court, or the sides of a building.
Calculate the area in each case.
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265
OTHER AREAS
TRIANGLES
Investigation 2
The area of a triangle
GRAPH
PAPER
You will need:
scissors, ruler, pencil and square centimetre graph paper.
What to do:
1 Draw a 10 cm by 5 cm rectangle using the graph paper.
Draw in the dashed diagonal and colour one triangle green.
Cut out the two triangles, then place one on top of the other
so you can see they have identical shape.
Copy and complete:
The areas of the two triangles are ...... .
The area of each triangle is ...... the area of the rectangle.
10 cm
2 Draw a 10 cm by 4 cm rectangle using the graph paper.
Construct the triangles shown and colour in the pink region.
Now divide the pink triangle along the dashed line so you
form four regions.
10 cm
Using what you found in 1, copy and complete:
1
The areas of regions 1 and 2 are ......
The areas of regions 3 and 4 area ......
2
So, area 2 + area 3 = area 1 + area 4.
The total area of the pink triangle is ...... the area of the rectangle.
From the Investigation you should have
found that the area of a triangle is half the
area of a rectangle which has the same
base and height as the triangle.
5 cm
4 cm
4
3
Even though they have
different shapes, these
triangles have the same base
and height. They therefore
have the same area.
height
base
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95
base £ height
.
2
100
50
or
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0
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£ base £ height
2
5
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Area of triangle =
base
25
base
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MEASUREMENT
(Chapter 12)
Example 4
Self Tutor
Find the areas of the following triangles:
a
b
8 cm
7 cm
12 cm
15 cm
b Area of triangle
a Area of triangle
1
= £ base £ height
2
1
= £ 12 cm £ 8 cm
2
1
£ base £ height
2
1
= £ 15 cm £ 7 cm
2
=
= 48 cm2
= 52:5 cm2
PARALLELOGRAMS
height
Area of parallelogram = base £ height
base
We can demonstrate this formula by cutting out a triangle from one end of the
parallelogram and shifting it to the other end. The resulting shape is a rectangle with
the same base and height as the parallelogram.
DEMO
height
cut
base
base
Perform this demonstation for yourself using paper and scissors.
Example 5
Self Tutor
Find the area of:
6 cm
10 cm
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Area = base £ height
) A = 10 cm £ 6 cm
) A = 60 cm2
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(Chapter 12)
EXERCISE 12E
1 Find the areas of the following triangles:
a
b
c
5m
4.8 cm
8m
6m
5.2 cm
12 m
d
e
f
5.3 m
5 cm
8.5 m
3.5 m
3 cm
7m
2 Find the areas of the following parallelograms:
a
b
c
4 cm
5 cm
5m
9 cm
12 cm
2m
d
e
f
4 cm
8 cm
11 cm
7 cm
6 cm
5 cm
9 cm
8 cm
10 cm
3 Alice is buying 3 identical shade sails with the
dimensions shown. The shadecloth costs $17:00
per m2 .
a Find the area of shadecloth used.
b Find the total cost of the sails.
2.1 m
3.2 m
4 A perspex safety guard for one side of a staircase is
to be made with the dimensions shown. Find the area
of perspex required.
1.5 m
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5
In South Australia, the “Copper Triangle” is
the area bounded by the towns of Wallaroo,
Kadina, and Moonta.
Kadina and Wallaroo are about 9 km apart.
The direct distance from Moonta to the
Rosslyn Road turnoff is about 14:6 km.
Estimate the size of the Copper Triangle.
9 km
Rosslyn Rd
turn off
14.6 km
© MapData services Pty Ltd 2011 (www.mapdataservices.com)
modified by permission
Have you ever thought how you could determine the
area of a shape which is not regular?
For example, consider the figure alongside:
We can estimate the area by drawing grid lines across
the figure.
We count all the full squares, and as we do so we cross
them out.
Now we have to make a decision about the part squares
inside the shape. We can count squares which are more
than half full as 1, and those less than half full as 0.
We hope that errors will cancel each other out when
we add all of these together.
We thus estimate the total area to be 26 square units.
What to do:
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1 Estimate the shaded areas:
a
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MEASUREMENT
2 Place your hand on cm2 grid paper
and trace around the outside.
a Estimate the area of your hand
in cm2 .
(Chapter 12)
269
PRINTABLE
GRID PAPER
b Do you think your estimate will be more or
less accurate if your fingers are together or
apart? Explain your answer.
3
a Estimate the area of the sole of your shoe.
b Estimate the area of your bare foot.
VOLUME
F
This stone
occupies more space than this pebble.
We say that the stone has greater volume than the pebble.
The volume of a solid is the amount of space it occupies.
This space is measured in cubic units.
As with area, the units used for volume are related to the units used for length.
1 cubic millimetre (mm3 ) is the volume of a cube with a side of length 1 mm.
1 cubic centimetre (cm3 ) is the volume of a cube with a side of length 1 cm.
1 cubic metre (m3 ) is the volume of a cube with a side of length 1 m.
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MEASUREMENT
(Chapter 12)
RECTANGULAR PRISMS
A rectangular prism is a 3-dimensional solid with 6 rectangular faces.
For example, a 4 £ 2 £ 3 prism is shown alongside.
Clearly there are 3 layers, and each of these layers
contains 4 £ 2 = 8 cubes.
3
So, there are 8 £ 3 = 24 cubes altogether.
2
The volume is 4 £ 2 £ 3 = 24 units3 .
4
This leads to the following rule for volume:
Volume of a rectangular prism = length £ width £ height
EXERCISE 12F
1 Find the number of cubic units in each of the following solids:
a
b
c
d
e
f
2 Arrange these rectangular prisms in ascending order of volume, from the lowest number of
cubic units to the highest:
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Example 6
271
(Chapter 12)
Self Tutor
Find the volume of this
rectangular prism:
8 cm
6 cm
10 cm
Volume = length £ width £ height
= 10 cm £ 6 cm £ 8 cm
= 480 cm3
3 Find the volume of the following rectangular prisms:
a
b
c
4 cm
4m
3 cm
20 cm
25 cm
8m
15 m
d
e
5 cm
6 cm
f
5m
3 mm
4 cm
2m
9 cm
4 The rectangular prism alongside has a volume of 36 cm3 .
Show that there are exactly 8 different rectangular prisms
with whole number sides that have a volume of 36 cm3 .
There is no need to draw them.
5
3 cm
4 cm
3 cm
Find:
a the volume of this prism
b the sum of the areas of its six faces.
6 An industrial vat measures 2:2 m by 3:1 m by 1:1 m
high. It is filled with dye to a level 15 cm from the top.
What volume of dye is in the vat?
Be careful
with units!
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7 Answer the Opening Problem on page 254.
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MEASUREMENT (Chapter 12)
8 Illustrate a method of packing the smaller
boxes into the larger box.
How many boxes can be packed?
3 cm
6 cm
6 cm
3 cm
9 cm
12 cm
KEY WORDS USED IN THIS CHAPTER
² area
² metre
² square unit
² cubic unit
² perimeter
² volume
1 Convert:
a 356 cm to m
² length
² rectangular prism
b 450 m to km
c 7:63 m to mm.
2 Find the perimeter of:
a
b
10 cm
13 cm
4.6 km
12.1 km
3 Find the area of each polygon:
a
b
c
3 cm
6m
4 cm
6 cm
5 cm
8m
9m
a How many 2 cm by 3 cm stamps can fit on a sheet
20 cm by 30 cm?
b If each stamp costs 60 cents, what is the cost of half a
sheet?
4
15 cm
5 A yachting line contains 30 flags
with the dimensions shown. Find the
area of material required to make the
flags on the line.
20 cm
6 Find 375 cm + 2:1 m + 340 mm.
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7 How many 10 cm £ 6 cm £ 10 cm boxes can fit into a container with dimensions
1:2 m £ 1:2 m £ 1:2 m?
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MEASUREMENT (Chapter 12)
6m
8 A room with this floorplan is to have a skirting
board fitted to the bottom of each wall. The
skirting board costs $16:50 per metre.
a Find the total length of skirting board required.
b What is the total cost of the skirting board?
9 Find the volume of:
a
2m
4m
8m
b
c
5 cm
4 cm
8 cm
10 cm
1 The formula for the area of the parallelogram shown
alongside is:
A
1
£b£h
2
B b£l
D b£h£l
h
C b£h
E h£l
l
b
2 The perimeter of the figure alongside is:
A 90 mm
D 81 mm
273
B 81 cm
E 81 mm2
3
15 mm
2
C 90 mm
18 mm
The area of the triangle is:
9 cm
A 36 cm2
D 72 m2
7 cm
B 28 cm2
E 31:5 cm2
C 56 cm2
8 cm
4 The volume of the rectangular prism is:
A 30 cm3
D 36 cm3
B 11 cm3
E 24 cm3
C 30 mm3
3 cm
2 cm
6 cm
5 The area of a book cover would most likely be measured in:
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MEASUREMENT (Chapter 12)
6 The figure below has
the same area as:
A
B
D
E
C
7 The number of cubic units in the solid is:
A 30
B 36
C 24
D 42
E 48
8 The area of the parallelogram is:
A 18 cm2
D 6 m2
B 18 m2
E 54 m2
C 27 m2
2m
6m
9m
9 9 m + 38 cm + 40 mm is equal to:
A 9:384 m
B 978 cm
C 47:4 cm
D 942 cm
E 934 cm
10 The perimeter of the triangle is:
A 59:2 cm
D 11:5 cm
B 131:2 mm
E 18:7 cm
C 1870 mm
8 cm
45 mm
6.2 cm
1 Find the perimeter of:
a
b
15 cm
2.5 m
24 cm
2 Grant competes in the 100 m, 200 m, 400 m, and 1500 m freestyle events during a swim
meet. How many kilometres has he swum in total?
3 Write these measurements in ascending order: 423 mm, 21 cm, 0:35 m, 47:1 mm.
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4 A square has an area of 49 cm2 . Find the length of its sides.
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MEASUREMENT (Chapter 12)
5 A billiard table has the dimensions shown.
The cloth which covers the table costs $49 per
square metre.
Find the cost of covering the table.
275
2.8 m
1.4 m
6 Find the areas of the following polygons:
a
b
4 cm
3 cm
5 cm
6 cm
5 cm
7 A park is surrounded by two sets of parallel roads
as illustrated.
Find the area of the park.
120 m
150 m
250 m
8 Find the volumes of these rectangular prisms:
a
b
5 mm
8 mm
2m
3 mm
9 A book is 15 cm long, 10 cm wide, and 2 cm high. Find the volume of the book.
10 Find 2:63 m + 50 mm + 122 cm.
Practice test 12C
Extended response
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Raisins
1 Small boxes of raisins with dimensions 5 cm
by 6 cm by 15 cm, need to be packed into the
larger boxes shown.
s
20 cm
Raisin
a Find the volume of the box of raisins.
15 cm
b Find the volume of the large box.
12 cm
c Find the maximum number of raisin boxes
5 cm 6 cm
30 cm
that will fit into the large box.
d Illustrate a method of packing the maximum amount of raisin boxes into the large
box.
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MEASUREMENT (Chapter 12)
2
Toby is landscaping his backyard. He needs to pave
the area shown with square pavers 25 cm by 25 cm.
2m
a By dividing the area into two rectangles, find
the total area to be paved.
b Find the area, in square metres, of one paver.
c How many pavers will Toby need?
d The pavers cost $3:50 each. How much money
will Toby need to buy all of the pavers he
needs?
6m
6.5 m
5m
3 A city council is putting a new concrete kerb
around the block shown:
75 m
a How many metres of kerb will need to be
laid?
60 m
b If the kerb costs $45 for each metre, how
much will it cost the council?
c The council wishes to put small trees along
120 m
the kerb. The trees need to be spaced 3 m
apart, to allow for driveways.
i How many trees are needed to go around the whole block?
ii If the trees cost $50 each, how much will the council spend on trees?
4
A warehouse has cubic boxes stacked on pallets
as shown.
a How many boxes are on the pallet?
b If each box is 20 cm £ 20 cm £ 20 cm, find
the volume of one box.
c Explain why the total volume of boxes on the
pallet is 736 000 cm3 .
d Each box weighs 5 kg, and the pallet weighs
35 kg. A small forklift owned by the
warehouse has a maximum lift of 500 kg.
Will the forklift be able to lift the pallet?
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a A brand of toilet paper is sold in rolls of 190 sheets.
If each sheet of toilet paper is 11 cm long, how many
metres of toilet paper are in:
i one roll
ii an 8-roll pack?
b The company brings out a new ‘long roll’ of toilet
paper. Each roll has 255 sheets, but only 6-roll packs
are sold.
i If each sheet of toilet paper in the new roll is
still 11 cm, how many metres of toilet paper
are in the 6-roll pack?
ii How many more metres are in this new pack than in the old 8-roll pack?
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