Skills for working lifeSkills for working life

FractionsFractions

Outcomes from this sessionOutcomes 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

What is a fraction?What is a fraction?

Definition ‘ A Part of a whole’Definition ‘ A Part of a whole’

Comparing FractionsComparing FractionsBefore you can compare fractions the bottom (denominator) must be the same.

e.g. Which is the smaller

5 OR 18 2

This becomes 1 x 4 = 4 2 4 8

4 Is smaller than 5 8 8

Therefore 1 is smaller2

Comparing FractionsComparing Fractions

Which is smaller? 1 or 3 4 8

1 X 2 = 2 4 2 8

1/4 is smaller than 3/8

Comparing FractionsComparing Fractions

Which is smaller?

1. 2 or 6

5 10

2. 5 or 3 8 4

Answer

2 x 2 = 4 5 2 10 2 is smaller than 6 5 10

Answer 3 x 2 = 6 4 2 8 5 is smaller than 3 8 4

Questions

Which is the larger?

1. 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

FractionsFractionsIn 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 = 45 5

But we have 2 4 x 2 = 8 5

FractionsFractions

4 of 30 5

Divide by 5 , then multiply by 4

1 of 30 = 6 5

6 x 4 = 24

QuestionsQuestions1. 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

12

30

20

24

25

10

20

33

66

9

18

ApplicationApplication

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?

Original order is for 40 peopleNew order 30 people

He needs only 30 of the food 40

30 Is the same as 340 4

e.g. 3 hummus x 40 = 120 total

But we only need 3 4First work out ¼ of 120 = 30

30 X 3 = 90 hummus are now required

Group workGroup 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

QuestionsQuestions

As a group or with another person , try these

1. 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

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

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

116

18

316

38

14

A. Was green or silver colour the most popular

B. Was red or blue the most popular

C. What do all the fractions add up to?

D. Out of the 160 cars , 100 are 1.6 litre engines. What fraction is that?

Silver

Blue

1

100/160 = 5/8

4. Change the following into fractions of 1 hour?

a. 30 mins

b. 10 mins

c. 45 mins

d. 5 mins

30 = 1 60 2

10 = 1 60 6

45 = 3 60 4

5 = 1 60 12

Tim filled in his time sheet as follows:

Monday 7 Hours 30 mins

Tuesday 6 Hours 40 mins

Wednesday 7 Hours 10 mins

Fill in the last column to show the mixed fraction. How many hours did he claim in

total (as a mixed fraction).

7 1/2

6 2/3

7 1/6

7 3/6

6 4/6

7 1/6

21 1/3 hours