F4 IGCSE Inverse Proportion

Topic 7 Inverse Proportion

​Objectives

​•Understand the meaning of indirect proportion.

•Compare the concepts of direct proportion and indirect proportion.

•Solve problems independently by applying the knowledge and skills acquired.

Multiple Choice

Starter:

8 cows can graze a field in 28 days. How long would 4 cows take to graze the same field?

• More than 28 days

• Fewer than 28 days

• Unpredictable

Inverse Proportion

Multiple Choice

Which statement best describes an inverse proportion relationship between y and x?

• y increases then x will decrease

• y increases then x will increase

• y increases then x will remain the same

• y decreases then x will decrease

Multiple Choice

Given that y is inversely proportional to x, what is the general equation?

Inverse Proportion - General Equation

Multiple Choice

Which graph represents an inverse proportion relationship?

Inverse Proportion - Graph(s)

Solve problems related to Inverse Proportion

Read the question carefully to solve the problems.

​

Apply the knowledge and skills learned in the previous lesson about direct proportion to increase the accuracy.

​

​Write down any difficult questions on your classwork book.

Multiple Choice

Say 'TRUE' or 'FALSE'
The population of a country and the area of land per person are inversely proportional

• TRUE

• FALSE

Multiple Choice

Identify whether the given relation is Direct or Indirect Proportion?
The number of workers on a job and the time to complete the job

• Direct Proportion

• Inverse Proportion

Multiple Choice

Identify whether the given relation is Direct or Indirect Proportion?
Area of cultivated land and the crop harvested 

• Direct Proportion

• Inverse Proportion

Multiple Select

Try it again:

8 cows can graze a field in 28 days. How long would 4 cows take to graze the same field?

• 48

• 56

• 36

• 40

Multiple Select

12 men can dig a pond in 8 days. How many men can dig it in 6 days?

• 20

• 15

• 16

• 24

Multiple Choice

Given that y is inversely proportional to x and y =0.25 when x =4, find the value of y when x =5.

• 0.1

• 0.2

• 1

• 2

Multiple Choice

Given the inversely proportional relationship, find the value of x when y=6.

• x=6

• x=-6

• x=-6 or +6

• x=4

Multiple Choice

T is inversely proportional to P

When T is 20, P is 4

Which formula would link T and P?

• $$T\ =\ \frac{5}{P}$$

• $$T=80P$$

• $$T\ =\ 5P$$

• $$T\ =\ \frac{80}{P}$$

Multiple Choice

It is given that p is inversely proportional to q - 3 . When p is 20, q is 8. Find an equation connecting p and q.

Fill in the Blanks

A tank is used to store water. If water is used at a rate of 100 litres/day the tank will be empty in 40 days. How long will the water last if it is used at a rate of 50 litres/day? (unit is not required)

Show your steps on the classwork book

Multiple Choice

• 4

• 25

• 100

• 10

Multiple Choice

• 90

• 40

• 2.25

• 60

Multiple Choice

• a³

• 8a³

• 5.5

• 25

Draw

Spot the mistake(s)!

Open Ended

Plenary:

Give a real life example of two quantities which are inversely proportional to each other.

Poll

How do you find the topic about inverse proportion?

• Very Easy

• Not too easy. Need more practice.

• Very difficult

• Need more practice on algebra