Year 8

# The constant of proportionality

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## Lesson details

### Key learning points

- In this lesson, we will learn about the the term 'constant of proportionality' and how it relates to how proportion works.

### Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

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### 5 Questions

Q1.

Which graph does not show to direct proportion?

A

B

Q2.

Which graph shows direct proportion?

B

C

Q3.

Which table does not shows direct proportion?

A

B

Q4.

Which table does not shows direct proportion?

B

C

Q5.

x and y are directly proportional as shown in the graph. What is the value of y when x = 10?

20

22

### 8 Questions

Q1.

Complete the sentence: When two quantities are in ........................ , when one variable doubles, the other doubles too.

constant of proportionality

indirect proportion

Q2.

Complete the sentence: When two quantities are in direction proportion, when one variable is zero, the other is .............

10

2

Q3.

x and y are in direction proportion. When x is 4 y is 11. What is the value of y when x = 12?

23

5

Q4.

The cost of T shirts online at £12 each. The postage charge is £3.50 per order. How much will it cost to order 2 T shirts?

£24

£31

Q5.

Think about the previous question: Are the number of T-shirts and the cost in direct proportion?

Yes

Q6.

Which table shows direct proportion?

Option 2

Option 3

Q7.

What is the constant of proportionality in the table below?

10

2

Q8.

What is the constant of proportionality between m and n?

4

5