1 Chapter 21 – Direct and Inverse Proportion Subject: Mathematics (0580) Topic: Algebra Worksheet No.: W21 Term, Year: Term 1 Name: Class: Date: Learning Objectives: C 21.1 & 21.2 - Express direct and inverse proportion in algebraic terms and use this form of expression to find unknown quantities. 21.1 Direct Proportion
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4 MCE Cambridge IGCSETM Mathematics Exercise 21.1 Page 501
5 21.2 Inverse Proportion
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7 MCE Cambridge IGCSETM Mathematics Exercise 21.2 Page 506
w is proportional to the square root of y. y is inversely proportional to x. When x = 4, y = 16 and w = 8. Find w in terms of x. 1 w = ................................................... [3] [Total: 3] y is inversely proportional to the cube of . y = 9.45 when x = 3. Find y when x = 4. 2 y = ................................................... [3] [Total: 3] 1
y is directly proportional to the cube root of (x + 1). When x = 7, y = 1. Find the value of y when x = 124. 3 y = ................................................... [3] [Total: 3] y is inversely proportional to the square root of (x + 4). When x = 5, y = 2. Find y when x = 77. 4 y = ................................................... [3] [Total: 3] z is inversely proportional to the square of . When y = 5, z = 9. Find z in terms of y. 5 z = ................................................... [2] [Total: 2] The force of attraction, F Newtons, between two magnets is inversely proportional to the square of the distance, d cm, between the magnets. 6 2
When d = 1.5, F = 48. (a) Find an expression for F in terms of d. F = ................................................... [2] When the distance between the two magnets is doubled the new force is n times the original force. Work out the value of n. (b) n = ................................................... [1] [Total: 3] y is directly proportional to the square root of . When x = 28, y = 20. Find y when x = 39. 7 y = ................................................... [3] [Total: 3] 3
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Question Answer Marks 2 final answer 5 2 final answer 6(a) 1 or 0.25 6(b) 7 24 3 - Mark
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