Decimals And Ratio Worksheet Page 6

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MASTER
P149
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5
Real / Problem-solving
2p coins used to be made from a mix of
6.5
copper, tin and zinc in the ratio 95 : 3.5 : 1.5.
STEM: Using ratios
a A 2p coin had a mass of 7 g. What were the masses of copper, tin
and zinc in the coin?
You will learn to:
b Sally had £1 in 2p pieces. What was the total mass of the coins?
Solve engineering problems using ratio and proportion
6
Real
Turquoise paint is made by mixing blue, green and yellow in the
Q6 hint
Use unit ratios.
ratio 2.5 : 1.4 : 0.1.
Simplify the ratio into whole numbers.
Copy and complete the table to show how much of each colour is
Then share the amount of paint in the
needed to make the quantities shown.
new ratio.
Fluency
Size
Blue
Green
Yellow
Simplify each ratio.
1 litre
4 : 7
4 : 8
6 : 16
1.5 litres
5 : 20
3 : 5
24 : 28
Explore
2.5 litres
Can all the ratios be simplifi ed?
Why learn this?
How do mountain bikes get up
7
Real / Reasoning
A photo-printing service offers the following picture
Most machines have gears, and gears depend
steep hills?
sizes:
on ratios.
6 × 4 inches, 7 × 5 inches, 8 × 6 inches, 10 × 8 inches, 12 × 8 inches.
A digital camera takes photographs in the ratio 3 : 2.
Exercise 6.5: Engineering ratios
Which sizes of photo can be printed from this camera?
8
STEM
The aspect ratio describes the ratio ‘width : height’ of an image.
1 Divide each quantity in the ratio given.
Q8 hint
Most modern televisions have an aspect ratio of 16 : 9.
a 567 kg in the ratio 5 : 1
How high would screens be with these widths?
A screen 16 cm wide would be
b 486 metres in the ratio 3 : 2
9 cm tall.
a 32 cm
b 30.5 cm
c 41.7 cm
d 44.3 cm
c £7816 in the ratio 2 : 3 : 5
How wide would screens be with these heights?
e 27 cm
f 17.5 cm
g 26.4 cm
h 35.2 cm
2 Simplify each ratio into a whole number ratio in its simplest form.
a 5.2 : 4.5
b 8.2 : 6.3
9
Reasoning
The triathlon is a race where competitors swim, cycle and
run. Four recognised lengths of race are shown in the table below.
c 8.5 : 2.25
d 2.56 : 1.37
Race
Swim
Cycle
Run
3 Wood’s metal is an alloy made from bismuth, lead, tin and cadmium.
Sprint
0.75 km
20 km
5 km
Mixing these amounts will make 1 kg of Wood’s metal.
Olympic
1.5 km
40 km
10 km
bismuth
500 g
Half Ironman
1.9 km
90 km
21.1 km
Q9a hint
lead
250 g
Ironman
3.8 km
180.2 km
42.2 km
First fi nd the total distance of the race.
tin
125 g
a What proportion of the Sprint triathlon is running?
Then write the proportion for ‘run’ as
cadmium
125 g
b Cycling is Tom’s strongest sport. Which race or races would give
a fraction, and simplify.
him the best chance of winning?
How much of each metal is needed to make 2.5 kg?
10
Explore
Why do some old TV programmes have space at the sides
of the screen?
Worked example
Key point
What have you learned in this lesson to help you answer this
A new TV has aspect ratio of 16 : 9. Express this as a unit ratio .
You can compare ratios by writing
question? What other information do you need?
them as unit ratios . In a unit ratio,
Give your answer to two decimal places.
11 Refl ect
one of the two numbers is 1.
16 : 9
a Look back at Q5a. Write all the steps you took to work out the
Divide both sides of the ratio
÷ 9
÷ 9
answer.
by the smallest number, 9
1.78 : 1
b Look back at Q9. Write the steps you took to work out the answer.
c Lou says, ‘Question 5 was about ratio. A ratio compares one part
Q11c hint
to another part. Question 9 was about proportion. A proportion
Use your steps for Q5a and Q9
4 Write each ratio as a unit ratio .
compares one part to the whole thing.’
to help you.
Give each answer to a maximum of two decimal places.
Is Lou correct?
a 9 : 5
b 11 : 4
c 17 : 33
d 11 : 23
145
Theta 1, Section 6.4
Unit 6 Decimals and ratio
146

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