Direct & Inverse Proportion (OCR GCSE Maths)

Exam Questions

3 hours51 questions
1
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3 marks

Yesterday it took 5 cleaners 4 1 half  hours to clean all the rooms in a hotel.

There are only 3 cleaners to clean all the rooms in the hotel today.

Each cleaner is paid £8.20 for each hour or part of an hour they work.

How much will each cleaner be paid today?

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2
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3 marks

p spaceis inversely proportional to t.

When space t space equals space 4 comma space p space equals space 12

Find the value of space p space when  t space equals space 6

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3
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3 marks

d is inversely proportional to c

When c space equals space 280 comma space space d space equals space 25

Find the value of d when c space equals space 350

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4
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3 marks

y is inversely proportional to x

Whenspace x equals space 1.5 comma space y space equals space 36 space

Find the value of y when x space equals space 6

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5a
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3 marks

At a depth of x metres, the temperature of the water in an ocean is T to the power of ring operator C.
At depths below space 900 spacemetres, T is inversely proportional tospace x.

T is given by

            T space equals space 4500 over x

Work out the difference in the temperature of the water at a depth of space 1200 space metres and the temperature of the water at a depth of space 2500 spacemetres.
5b
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1 mark

Here are four graphs.

q5b-medium-3-4-direct-and-inverse-proportional-edexcel-gcse-maths

One of the graphs could show that T is inversely proportional to x.

Write down the letter of this graph.

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6
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5 marks

Carol makes birthday cards.
Each card takes the same amount of time to make.

She makes 3 cards in 48 minutes.
She has an order for 80 cards.

Can she complete this order in 3 days if she works 8 hours each day?
Show how you decide.

..................... because
.............................................................................

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7
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3 marks

y is inversely proportional to x.
y = 0.04 when x = 80.

Find the value of y when x = 32.

= ...................

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8
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2 marks

The table shows values of x and y.

x 4 16 36
y 6 3 2

Show that these values fit the relationship that y is inversely proportional to begin mathsize 16px style square root of x end style .

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9a
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2 marks

Sam and two friends put letters in envelopes on Monday.
The three of them take two hours to put 600 letters in envelopes.

On Tuesday Sam has three friends helping.

Working at the same rate, how many letters should the four of them be able to put in envelopes in two hours?

9b
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4 marks

Working at the same rate, how much longer would it take four people to put 1000 letters in envelopes than it would take five people?

9c
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2 marks

Sam says

It took two hours for three people to put 600 letters in envelopes.
If I assume they work all day, then in one day three people will put 7200 letters in envelopes because 600 × 12 = 7200.


Why is Sam’s assumption not reasonable?
What effect has Sam’s assumption had on her answer?

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10a
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5 marks

Donald swims 3 lengths of a swimming pool in 93 seconds.

i)
Use this information to show that he could swim 100 lengths in under 55 minutes.

[4]

ii)
What assumption did you make in part (i)?

[1]

10b
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1 mark

Donald tries to swim the 100 lengths in under 55 minutes.

Suggest one reason why he might not achieve this.

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11a
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3 marks

T is directly proportional to the cube of  r

T space equals space 21.76 when r space equals space 4

Find a formula for T in terms of r.

11b
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1 mark

Work out the value of T when r space equals space 6.

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12
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2 marks

y spaceis inversely proportional to x.

Complete the table.

x 12 6  
y   4 8

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13
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4 marks

The diagrams show the position of a tap when off and fully on.

The tap is fully on when the angle of turn is 180°

q9-1-paper-2h-nov-2018-aqa-gcse-maths

When fully on, water flows out of the tap at 14 litres per minute.
The rate at which water flows out is in direct proportion to the angle of turn.
The tap is turned 135°

q9-2-paper-2h-nov-2018-aqa-gcse-maths

The water flows into a tank with a capacity of 79.8 litres.
Will it take less than 7 1 half minutes to fill the tank?

You must show your working.

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14a
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3 marks

To complete a task in 15 days a company needs

4 people each working for 8 hours per day.

The company decides to have

5 people each working for 6 hours per day.

Assume that each person works at the same rate.

How many days will the task take to complete?
You must show your working.

14b
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1 mark

Comment on how the assumption affects your answer to part (a).

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15
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1 mark

y is directly proportional to x.

Which graph shows this?

Circle the correct letter.

q4-paper3h-specimen2015-aqa-gcse-maths

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1
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4 marks

y is directly proportional to the square of x.

When x space equals space 3 comma space y space equals space 36

Find the value of y when x space equals space 5

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2
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3 marks

h is inversely proportional to the square of r.

When space r equals 5 comma space h equals 3.4

Find the value of h when r space equals space 8

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3
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4 marks

Given that y space proportional to space 1 over x squared, complete this table of values.

x 1 2 5 10
y       1

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4
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3 marks

The intensity of the sound, I watts/m2, received from a loudspeaker is inversely proportional to the square of the distance, d metres, from the loudspeaker.

When d space equals space 2 comma space I space equals space 30
Work out the value of I when d space equals space 10

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5
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3 marks

T is inversely proportional to d squared
T space equals space 12 spacewhen d space equals space 8

Find the value of T when d space equals space 0.5

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6
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2 marks

LJeW5o9-_q6-hard-3-3-direct-and-inverse-proportional-edexcel-gcse-maths

The graphs of y against x represent four different types of proportionality.

Match each type of proportionality in the table to the correct graph.

Type of proportionality Graph letter
y space proportional to space x  
y space proportional to space x squared  
y space proportional to space square root of x  
y space proportional to space 1 over x  

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7
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3 marks

A company has to make a large number of boxes.

The company has 6 machines.
All the machines work at the same rate.
When all the machines are working, they can make all the boxes in 9 days.

The table gives the number of machines working each day.

  day 1 day 2 day 3  all other days
Number of machines working 3 4 5 6

Work out the total number of days taken to make all the boxes.

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8
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4 marks

Three people take 2 1 half hours to deliver leaflets to 270 houses.

Assuming all people deliver leaflets at the same rate, how long will it take five people to deliver leaflets to 405 houses?
Give your answer in hours and minutes.

................. hours ................. minutes 

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9
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3 marks

y is inversely proportional to the square root of x.
y is 40 when x is 9.

Find a formula linking x and y.

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10
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3 marks

The graph shows the speed, v metres per second (m/s), of a car at time t seconds.

q15-paper4-june2017-ocr-gcse-maths

The speed of this car is directly proportional to the square of the time.

Find a formula linking v and t.

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11
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3 marks

A is inversely proportional to C squared

A = 40 when C = 1.5

Calculate the value of C when A = 1000

C space= ...................................................

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12a
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3 marks

R is proportional to t squared
The graph shows the relationship between R and t for 0 space less-than or slanted equal to space t space less-than or slanted equal to space 4

q16-paper2h-june2018-edexcel-igcse-maths

Find a formula for R in terms of t.

12b
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2 marks

Given also that R space equals fraction numerator 8 over denominator 5 x end fraction
show that t is inversely proportional to square root of x for t space greater than space 0

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13
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3 marks

F is inversely proportional to the square of v.

Given that F space equals space 6.5 when v space equals space 4

find a formula for F in terms of v.

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14a
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3 marks

T is inversely proportional to m squared

T space equals space 30 when m space equals space 0.5

Find a formula for T in terms of m.

14b
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1 mark

Work out the value of T when m space equals space 0.1

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15a
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3 marks

The following table gives values of space x spaceand y where y is inversely proportional to the square of space x space.

x 1.5 2 3 4
y 16 9 4 2.25

Find a formula for y in terms of x.

15b
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2 marks

Given that x greater than space 0

find the value of x when y space equals space 144.

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16a
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3 marks

P  is inversely proportional to square root of space q space end root
P  = 10 when q space equals space 0.0064

Find a formula for space P space in terms of q.

16b
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2 marks

Find the value of space q space when  P = 20.

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17a
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3 marks

y is inversely proportional to square root of x

      y space equals space 4     when     x space equals space 9


Work out an equation connecting y and x.

17b
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2 marks

Work out the value of y when x space equals space 25.

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18
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3 marks

15 machines work at the same rate.
Together, the 15 machines can complete an order in 8 hours.

3 of the machines break down after working for 6 hours.
The other machines carry on working until the order is complete.

In total, how many hours does each of the other machines work?

............................hours

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19
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1 mark

V equals k over H  where k is a constant.

Which two statements are correct?

Tick two boxes.

begin mathsize 26px style square end style V is directly proportional to H
begin mathsize 26px style square end style V is inversely proportional to H
begin mathsize 26px style square end style V is directly proportional to 1 over H
size 26px square V is inversely proportional to 1 over H

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20
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1 mark

x y space equals space c where c is a constant.
Circle the correct statement.

y is directly proportional to x y is directly proportional to 1 over x
y is inversely proportional to 1 over x x is directly proportional to y

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1a
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2 marks

The table shows a set of values for x and y.

x 1 2 3 4
y 9 2 1 fourth 1 9 over 16

y is inversely proportional to the square of x.

Find an equation for y in terms of x.
1b
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2 marks

Find the positive value of x when y equals 16.

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2
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3 marks

y is directly proportional to cube root of x

y space equals space 1 1 over 6 when  x equals 8

Find the value of y when x equals 64

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3
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5 marks

y is inversely proportional to d squared
When d space equals space 10 comma space y equals 4

d is directly proportional to x squared
When x space equals space 2 comma space d space equals space 24

Find a formula for y in terms of x.
Give your answer in its simplest form.

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4
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3 marks

A pendulum of length space L space cm has time period T seconds.
T is directly proportional to the square root of L.

The length of the pendulum is increased by 40%.

Work out the percentage increase in the time period.

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5
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1 mark

D is directly proportional to the cube of n.
Mary says that when n is doubled, the value of D is multiplied by 6

Mary is wrong.
Explain why.

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6
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2 marks

These graphs show four different proportionality relationships between y and x.

q6-hard-3-3-direct-and-inverse-proportional-edexcel-gcse-maths

Match each graph with a statement in the table below.

Proportionality relationship Graph letter
y is directly proportional to x  
y is inversely proportional to x  
y is proportional to the square of x  
y is inversely proportional to the square of x  

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7
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4 marks

h is inversely proportional to p
p is directly proportional to square root of t

Given that h space equals space 10 and t space equals space 144 when p space equals space 6
find a formula for h in terms of t

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8
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4 marks

y is directly proportional to the square of x.

Find the percentage increase in y when x is increased by 15%.

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9
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4 marks

At a constant temperature, the volume of a gas V is inversely proportional to its pressure p.
By what percentage will the pressure of a gas change if its volume increases by 25%?

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10
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4 marks

x is directly proportional to y.
y is directly proportional to z.

When x = 10, y = 60.
When y = 8, z = 1.6.

Find a formula for z in terms of x.

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11
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4 marks

y is inversely proportional to square root of x
x is directly proportional to T cubed


Given thatspace y space equals space 8 space when T space equals space 25
find the exact value of space T spacewhen y space equals space 27

T space equals space......................................................

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12a
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3 marks

y is directly proportional to the cube of x

y space equals space 20 space h spacewhen x space equals space h space space space space space space left parenthesis h space not equal to space 0 right parenthesis

Find a formula for y in terms of space x spaceand h

y = .....................

12b
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2 marks

Find x in terms of h when y space equals space 67.5 space h
Give your answer in its simplest form.

x space=.......................

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13a
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3 marks

A is inversely proportional to the square of r.

space A space equals space 5 spacewhen r space equals space 0.3.

Find a formula for A in terms of r.

13b
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3 marks

Find the value of A whenspace r space equals space 7.5 A

A space equals space.............................................

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14
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4 marks

Beth and Mia translate documents from Spanish into English.
A set of documents that would take Beth 8 days would take Mia 10 days.

Beth starts to translate the documents.
After 2 days Beth and Mia both work on translating the documents.

How many more days will it take to complete the work?
You must show your working.

......................days

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15a
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3 marks

y is directly proportional to x cubed

y space equals space 17   when   x space equals space 4

Work out an equation connecting y and x.

15b
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1 mark

m is inversely proportional to square root of r.

The value of space r spaceis multiplied by 4.

Circle what happens to the value of m.

cross times 2 cross times 16 divided by 2 divided by 16

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16
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5 marks

P comma space Q and space R spacehave positive values.

P is directly proportional to the square of Q.
When P space equals space 1.25 comma space Q space equals space 0.5
Q is inversely proportional to R.
When Q space equals space 0.5 comma space R space equals space 6

Work out the value of R when P space equals space 0.8

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