StarterStarter

What is:What is:

11 11 + + 6 6 22 B) B) 22 + + 33 C) C) 66 - - 22

2 4 3 6 12 32 4 3 6 12 3

Starter: Using a common Starter: Using a common denominatordenominator

1) Write any mixed numbers as improper fractions.

1 34

= 74

2) Find the lowest common multiple of 4, 9 and 12.

The multiples of 12 are: 12, 24, 36 . . .

36 is the lowest common denominator.

What is +19

?134

+512

3) Write each fraction over the lowest common denominator.

74

=36

×9

×9

63 19

=36

×4

×4

4 512

=36

×3

×3

15

4) Add the fractions together.

3663

+364

+3615

=36

63 + 4 + 15=

3682

= 2 3610

= 2 185

What is +19

?134

+512

Using a common denominatorUsing a common denominator

Fraction QuantitiesFraction Quantities

Objective: How to work with Objective: How to work with Fractions Fractions

Class questionClass question

Please write in your books an example of a Please write in your books an example of a fraction or percentage you have seen in fraction or percentage you have seen in the real world???the real world???

Discounts in stores ½ off or 50% offDiscounts in stores ½ off or 50% offVAT??VAT??Taxes?Taxes?Interest Rates??Interest Rates??Money?Money?

Finding a fraction of an amountFinding a fraction of an amount

We can see this in a diagram:

23

of £18 = £18 ÷ 3 × 2 = £12

23

of £18?What is

Let’s look at this in a diagram again:

710

of £20 = £20 ÷ 10 × 7 = £14

710

of £20?What is

Finding a fraction of an amountFinding a fraction of an amount

What is of 9 kg?4

7

To find of an amount we can multiply by 4 and divide by 7.4

7

We could also divide by 7 and then multiply by 4.

4 × 9 kg = 36 kg

36 kg ÷ 7 = =36

7kg 5

1

7kg

Finding a fraction of an amountFinding a fraction of an amount

56

of £24 =16

of £24 × 5

= £24 ÷ 6 × 5

= £4 × 5

= £20

56

of £24?What is

Finding a fraction of an amountFinding a fraction of an amount

When we work out a fraction of an amount we

multiply by the numerator

and

divide by the denominator

For example,

23

of 18 litres = 18 litres ÷ 3 × 2

= 6 litres × 2

= 12 litres

Finding a fraction of an amountFinding a fraction of an amount

ExamplesExamplesFind: a) Find: a) 22 of £ 28 b) of £ 28 b)33 of 45 sweets c) 1 of 45 sweets c) 1 22 of 15 m of 15 m 7 5 3 7 5 3 A)A)First, Find First, Find 11 of £28: 28 divide by 7 = 4, So, of £28: 28 divide by 7 = 4, So, 22 of £ 28 = 2x4=£8 of £ 28 = 2x4=£8 7 7 7 7 OrOr2x28 Divide by 7 = £ 82x28 Divide by 7 = £ 8

B) First, Find B) First, Find 11 of 45 sweets: 45 divide by 5 = 9 of 45 sweets: 45 divide by 5 = 9 55

So, So, 33 of 45 sweets = 3x9 = 27 sweets of 45 sweets = 3x9 = 27 sweets 55OrOr3x45 Divide by 5= 27 sweets3x45 Divide by 5= 27 sweets

Exercises 2B page 20Exercises 2B page 20

Questions 1-2Questions 1-2