Y9 Booster

Y9 BoosterLesson 3

Objectives – what we should be able to do by the end of the lesson

• Calculate percentages of quantities using a calculator

• Calculate percentage increases and decreases

Percentage target board 1 M3.1

Increase Decrease

£40 70 cm

300 g 1 kg

£12 650 m

by

10% 15% 100% 35% 12.5%

Increase 300 g 15%by

10% is

15% is 10% + 5%

30g 5% is 15g

= 30g + 15g = 45g

300g + 15% = 300g + 45g = 345g


Increase Decrease

£40 70 cm

300 g 1 kg

£12 650 m

by

10% 15% 100% 35% 12.5%

Decrease 70 cm 12.5%by

10% is 7 cm 2.5% is 1.75cm

12.5% is 10% + 2.5% = 7 cm + 1.75 cm = 8.75 cm

70 cm – 12.5% = 70 cm – 8.75 cm = 61.25 cm


Increase Decrease

£40 70 cm

300 g 1 kg

£12 650 m

by

10% 15% 100% 35% 12.5%

Using a calculator:

A 15% increase:

100% 15%

1 + 0.15

115%

1.15

Increase £25 by 15%:

£25 15%

25 x 1.15 = £28.75

Decrease 3km by 12.5%:

100%

12.5%

1 – 0.125 = 0.875

Decrease 3 km by 12.5% = 3 x 0.875 = 2.625 km

( we need to find 87.5%)


Increase Decrease

£70 83 cm

350 g 1 kg

£12.50 650 m

by

11% 17% 120% 38% 16.5%


Increase Decrease

£70 83 cm

350 g 1 kg

£12.50 650 m

by

11% 17% 120% 38% 16.5%

Calculation: 350 x 1.17


Increase Decrease

£70 83 cm

350 g 1 kg

£12.50 650 m

by

11% 17% 120% 38% 16.5%



Increase Decrease

£70 83 cm

350 g 1 kg

£12.50 650 m

by

11% 17% 120% 38% 16.5%

Calculation: 12.5 x 0.835


Increase Decrease

£70 83 cm

350 g 1 kg

£12.50 650 m

by

11% 17% 120% 38% 16.5%



Increase Decrease

£70 83 cm

350 g 1 kg

£12.50 650 m

by

11% 17% 120% 38% 16.5%

Calculation: 70 x - 0.2

Objectives – how have we done?

• Calculate percentages of quantities using a calculator

• Calculate percentage increases and decreases

Thank you for your attention

Y9 Booster

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