Skills for working life Fractions

1
Skills for working life Fractions
2
Outcomes from this session At the end of this
session you should be able to
Understand the relationship between unit
fractions and division when finding parts
Understand that there are different strategies
for finding fractional parts
3
What is a fraction?
Definition A Part of a whole
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Comparing Fractions
Before you can compare fractions the bottom
(denominator) must be the same.
e.g. Which is the smaller 5
OR 1 8
2
This becomes 1 x 4
4 2
4 8
4 Is smaller than 5
8 8 Therefore 1 is smaller 2
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Comparing Fractions
Which is smaller? 1 or 3
4 8
1 X 2 2
4 2 8
1/4 is smaller than 3/8


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Comparing Fractions

• Which is smaller?
• 1. 2 or 6
  
• 5 10
  
  

Answer 2 x 2 4
5
2 10 2 is smaller than 6 5
10
2. 5 or 3
8
4
Answer 3 x 2 6
4
2 8 5 is smaller than 3 8
4
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Questions

• Which is the larger?
• 1 7 3
• 3 8 4
• 2. 1 1 1
• 3 6 8

All can divide into 24
8 21 18
24 24 24
All can divide into 24
8 4 3 24
24 24
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Fractions
In a fraction the bottom number is the
denominator. This is the number that you divide
by to find one part
e.g. To find 1/5 , divide by 5
In a fraction the top is the numerator this shows
how many parts
e.g. to find 2 , divide by 5 , multiply by 2
5
2 of 20 1 of 20
4 5 5
But we have 2 4 x 2 8
5
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Fractions

• 4 of 30
• 5

Divide by 5 , then multiply by 4
1 of 30 6
5
6 x 4 24
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Questions
1. 2 of 15
7. 1 of 30 5
3 2. 4 of
15 8. 2
of 30 5
3 3. 3 of 50
9. 1 of 99 5

3 4. 2 of 50
10. 2 of 99 5
3 5. 3
of 40 11.
1 of 27 5
3 6. 5 of 40
12 2 of 27
8
3
6
10
12
20
30
33
20
66
24
9
25
18
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Application
Tony is having a Greek party for 40 people.
Unfortunately 10 people decide to cancel, so he
will need to reduce his food order to fit. He was
going to order 1 Stifado 3 Hummus and 2
drinks of Ouzo for each person How does Tony do
his calculations?
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• Original order is for 40 people
• New order 30 people
• He needs only 30 of the food
• 40
• 30 Is the same as 3
• 40 4
• e.g. 3 hummus x 40 120 total
• But we only need 3
• 4
• First work out ¼ of 120 30
• 30 X 3 90 hummus are now required

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Group work
In pairs , work out how many stifado and drinks
Tony will now need?
Original 40 x 1 40 stiffido ¾ of 40
¼ of 40 10 3 x 10 30 stifado are now
required Drink 40 x 2 drinks 80 total ¾ of
80 ¼ of 80 20 3 x 20 60 drinks required
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Questions

• As a group or with another person , try these
• My order for a party of 20 people who wanted
  three sandwiches and two drinks each has been
  changed to a party of 15.
• What should my order be?
  Sandwiches
• drinks

45
30
15
2. My order for 60 meals had to be changed when I
was told that 2/3 of the people were
vegetarians. How many vegetarian meals did I need
to order ? 3. ¾ of the 120 meals I was asked to
cook had to be chicken How many was that ?
4. 1/3 of the 600 meals that I make each month
are vegetarian. How many meals do I make with
meat?
40
90
400
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3. In a car assembly there are 160 built per
hour. The table below shows the colours that were
ordered in an hour.
RED
BLUE
BLACK
SILVER
GREEN
3 16
1 16
1 8
3 8
1 4

1. Was green or silver colour the most popular
2. Was red or blue the most popular
3. What do all the fractions add up to?
4. Out of the 160 cars , 100 are 1.6 litre engines.
   What fraction is that?

Silver
Blue
1
100/160 5/8
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• 4. Change the following into fractions of 1 hour?
• 30 mins
• 10 mins
• 45 mins
• d. 5 mins

30 1 60 2
10 1 60 6
45 3 60 4
5 1 60 12
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Tim filled in his time sheet as
follows
Monday 7 Hours 30 mins
Tuesday 6 Hours 40 mins
Wednesday 7 Hours 10 mins
7 1/2
7 3/6
6 2/3
6 4/6
7 1/6
7 1/6
21 1/3 hours
Fill in the last column to show the mixed
fraction. How many hours did he claim in total
(as a mixed fraction).