n5 num 25-dec-15created by mr. lafferty maths dept. ratio & proportion indirect proportion ratio...

N5 Num

21 Apr 202321 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.

Ratio & ProportionRatio & Proportion

Indirect Proportion

Ratio Calculations

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Direct Proportion

Sharing in a Ratio

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Starter QuestionsStarter Questionsw

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2. Calculate 20% of 220

(a) 123 (b) 202 (c) 0.09

1. 3x + 5 = 17

3. How many significant numbers

4. Car depreciates by 20% in its first year. I f it was bought new for £10 000. How much is it worth now.

N5 Num

21 Apr 202321 Apr 2023 Created by Mr. Lafferty Maths Dept.Created by Mr. Lafferty Maths Dept.ww

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1.1. Apply tabular method to Apply tabular method to solve problems involving solve problems involving ratios.ratios.

1 We are learning how to do ratio calculations.

2.2. Show appropriate Show appropriate working.working.

Ratio Calculations

Ratio & Ratio & ProportionProportion

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Ratio Calculations

Example : The ratio of boys to girls is 4:5. If there are 16 boys, how many girls are there.

boys girls

4 5

16 20x 4 x 4


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Ratio Calculations

Example : The ratio of cars to buses is 3:7. If there are 49 buses, how many cars are there.

cars buses

3 7

21 49x 7 x 7


N5 Num

21 Apr 202321 Apr 2023 Created by Mr. Lafferty Maths DepartmentCreated by Mr. Lafferty Maths Department

Now try N5 Lifeskills

Ex 1Ch7 (page 64)

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Are you on Target ?I can ?


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2. Calculate 30% of 340

(a) 103 (b) 2002 (c) 0.104

1. 2x - 7 = 15

3. How many significant numbers

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1. We are learning to calculate proportional division.

Ratio & Ratio & ProportionProportionProportional Division

1. Solve problems using appropriate layout.

2. Show appropriate working.

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the ratio 3:5. How much does each get ?

Raffles £8 → 4003 →

Are we expecting more or

less

3

8 400 £150

Make smaller fraction


Bill

2 5 0

Ben £250

Check !150 + 250

= 400

Proportional Division

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Example : Ryan and Ross share 24 cakes in the ratio 3:1. How many cakes does each get ?

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Ratio Cakes4 → 243 →


less

3

4 24 18


Ryan

6

Ross 6

Check !18 + 6 = 24

Proportional Division

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Ex 2Ch7 (page 66)

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2.

4. Calculate 4 5×5 8

1. Simplfy the ratio 85 : 25

Calculate 6.5% of 300

3. Find the mean, median and mode for

25, 20, 55, 20

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1. We are learning the term Direct Proportion.

1. Understand the idea of Direct Proportion.

2. Solve simple proportional problems.

Direct Proportion


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Example : The cost of 6 cakes is £4.20. Find the cost of 5 cakes.


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ProportionProportion

“ .. When you double the number of cakes you double the cost.”

Two quantities, (for example, number of cakes and totalcost) are said to be in DIRECT PROPORTION, if :

Direct Proportion

21 Apr 202321 Apr 2023

No. of cakes £6 → 4.205 →


less

5

6 4.20 £3.50


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Direct Proportion

Example : On holiday I exchanged £30 for $45.How many $ will I get for £50.

£ $30 → 4550 →


less

50

30 45 $75

Make bigger fraction


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Direct Proportion

Example : 300 pencils cost £6. How much will 200 cost.

Pencil £300 → 6200 →


less

200

300 6 £4



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Ex 3Ch7 (page 67)

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2.

1. Simplfy the ratio 95 : 35

Calculate 0.5 + 1.45 + 0.06

3. I s there a correlation between the two quanities. I f so describe it.

xx

x

x

xx

x

x

y

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1. We are learning the term Inverse Proportion.

1. Understand the idea of Inverse Proportion.


2. Solve simple inverse proportion problems.

Inverse Proportion

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Inverse proportion is when one quantity doublesand the other halves. The two quantities are said

to be INVERSELY PROPORTIONAL or (INDIRECTLY PROPORTIONAL) to each other.

Inverse Proportion

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Indirect Proportion

Example : If it takes 3 men 8 hours to build a wall.How long will it take 4 men.

Men Hours3 → 84 →


less

3

4 8 6



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Indirect Proportion

Example : It takes 10 workers 12 months to build a house. How long should it take 8 men.

Workers Months10 → 128 →


less

10

8 12 15

Make bigger fraction


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Now try LifeskillsEx 5

Ch7 (page 69)

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Have you updated your Learning

Log ?



n5 num 25-dec-15created by mr. lafferty maths dept. ratio & proportion indirect proportion ratio...

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