Printable · GCSE Foundation · ages 14-16

Equations of direct and inverse proportion worksheet — GCSE Foundation

Fifteen questions on "equations of direct and inverse proportion" — DfE statement R13. Print it, or print three versions so neighbours cannot copy by letter; the key gives the letter for each version.

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Equations of direct and inverse proportion worksheet — GCSE Foundation

Maths · GCSE Foundation · R13 · Equations of direct and inverse proportion · Non-calculator · 15 questions

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1.A printer prints at a constant rate. The time taken to print a batch of forms is inversely proportional to the printer's speed, in pages per minute. Printing at 20 pages per minute takes 15 minutes. Work out how long the same batch takes to print at 25 pages per minute. Give your answer in minutes.
(a)12
(b)10
(c)18.75
(d)20
2.Two quantities y and z are each in direct proportion to x, and are given by y = 3x and z = 7x. Work out the difference between the value of y and the value of z when x = 4.
y = 3x
(a)40
(b)16
(c)28
(d)4
3.y is directly proportional to x, so y = kx. When x = 2, the value of y is 10. Work out the value of k.
(a)20
(b)12
(c)8
(d)5
4.Two quantities x and y are in direct proportion. When x = 8, the value of y is 20. Work out the value of y when x = 14.
(a)26
(b)5.6
(c)28
(d)35
5.A coach journey of 240 km takes 3 hours. For this fixed distance the average speed needed is inversely proportional to the time taken. Work out the average speed needed to complete the same journey in 2 hours.
(a)160 km/h
(b)480 km/h
(c)120 km/h
(d)80 km/h
6.Tap A fills a swimming pool in 6 hours. Tap B pours water twice as fast as tap A. The time taken to fill the pool is inversely proportional to the rate of flow. Work out how long tap B takes to fill the pool.
(a)3 hours
(b)12 hours
(c)4 hours
(d)1.5 hours
7.y is directly proportional to x, and y = 7x. Work out the value of x when y = 35.
y = 7x
(a)5
(b)7
(c)28
(d)245
8.y is directly proportional to x, and y = 3x. Work out the value of y when x = 4.
y = 3x
(a)1
(b)12
(c)7
(d)34
9.For the pairs x = 6, y = 15 and x = 10, y = 25, which statement is correct?
(a)They are not in direct proportion, because y − x is different for each pair (9 and 15).
(b)They are not in direct proportion, because x + y is different for each pair (21 and 35).
(c)They are in direct proportion, because y ÷ x = 2.5 for both pairs.
(d)They are in direct proportion, because x × y = 90 and 250.
10.y is directly proportional to x. If the value of x is trebled (multiplied by 3), what happens to the value of y?
(a)y stays the same
(b)y is divided by 3
(c)y is trebled
(d)y increases by 3
11.y is inversely proportional to x, so y = k ÷ x. When x = 5, the value of y is 8. Work out the value of k.
(a)3
(b)1.6
(c)13
(d)40
12.x × y is used to test whether two quantities are in inverse proportion. For the pairs x = 4, y = 15 and x = 6, y = 10, which statement is correct?
(a)They are not in inverse proportion, because y ÷ x is different for each pair (3.75 and 1.67).
(b)They are in inverse proportion, because x × y = 60 for both pairs.
(c)They are in inverse proportion, because x × y = 40 for both pairs.
(d)They are not in inverse proportion, because x + y is different for each pair (19 and 16).
13.The number of biscuits, b, that each guest at a party receives is inversely proportional to the number of guests, g. Which equation could show this relationship?
(a)b = g ÷ k
(b)b = k + g
(c)b = kg
(d)b = k ÷ g
14.Two quantities x and y are inversely proportional. When x = 2, the value of y is 15. Work out the value of y when x = 5.
(a)6
(b)12
(c)30
(d)37.5
15.The number of tickets a group can afford is inversely proportional to the price per ticket. At £4 per ticket, the group can afford 12 tickets. Work out how many tickets the group can afford at £6 per ticket.
(a)6
(b)18
(c)12
(d)8

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