Make sure you have watched the above videos and are familiar with the rules before trying these questions. It is also good to time yourself while doing these questions so that you can work on the speed as well.

GCSE MATHS DIRECT AND INVERSE PROPORTIONS REVISION NOTES

DIRECT AND INVERSE PROPORTIONS

DIRECT AND INVERSE PROPORTIONS

• Direct Proportion
• Inverse Proportion
• Proportions Word Problems

DIRECT AND INVERSE PROPORTIONS

DIRECT PROPORTION

Y x X

Y = K x

K = Constant

• When one value increase the other increases as Well
• Greater the Forces is the extension in the spring Produced .

INVERSE PROPORTION

K = Constant

Y = k/x

• When one value increases Other decreases.
• If pressure increases decreases volume

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DIRECT PROPORTION

a) Write the proportional relation.

b) Convert it into equation using a constant k

c) Substitue the values to work out k

d) Complete the equation.

e) Use the equation to find unknown values.

x is directly proportional to the square of y.

If x is 1000 y is 20.

a) Write the proportionality equation.

b) Work our the value of x when y is 5

INVERSE PROPORTION

a) Write the proportional relation.

b) Convert it into equation using a constant k

c) Substitue the values to work out k

d) Complete the equation.

e) Use the equation to find unknown values.

y is inversely proportional to the cube of x

When y= 125, b= 0.1

Find the value of y when x is 0.25

PROPORTION WORD PROBLEMS

Q1 To make 20 Flapjacks, 200 g of Flour is required. How much flour is needed to make 30 Flapjacks.

Q2 If 20 m wire cost $30 how much will 25 m wire cost ?

Q3 To make a red cookie you require 20 g of flour and 60 of sugar. If you have 360 g of sugar how much flour will you need.

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