Make the variable given in brackets the subject of the equation.
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Question No. 2
Solve the following equations.
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Question No. 3
Describe how the area of a square varies with its length. Write down the relationship in mathematical terms.
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Question No. 4
Given that y varies as the square of x, and that y = 9 when x = 4, find:
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Question No. 5
If y varies directly as x varies, and y = 7 when x = 4:
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Question No. 6
Given that p varies as the square of q varies, and that p = 90 when q = 15,
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Question No. 7
Given that the surface area of a sphere, A, varies directly with the square of its radius, r, and that A = 4πr²:
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Question No. 8
If m is directly proportional to n and m = 3 when n = 18, find the value of m when n = 42.
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Question No. 9
Given that r varies directly as t varies, and r = 175 when t = 35,
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Question No. 10
The height, h, of water in a can varies directly as the time taken, t, to fill the can varies. Given that h = 4.2 cm when t = 10 seconds, find the time taken for the can to be filled to a height of 6.3 cm.
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Question No. 11
The volume of air in a sphere varies directly with the cube of its radius. The volume is 64 cm³ when the radius is 8 cm. Find the volume when the radius is 10 cm.
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Question No. 12
Given that y is directly proportional to the square of x and y = 40 when x = 2,
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Question No. 13
Given that m is inversely proportional to n and that m = 2 when n = 5, find:
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Question No. 14
The table represents the relationship ‘y varies inversely as x varies’. Find the values of a and b.
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Question No. 15
If y varies inversely as the square of x − 4 varies, write the equation relating y and x − 4, including the constant of proportionality.
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Question No. 16
If in question 1, y = 5 when x = 2, find:
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Question No. 17
Given that v varies inversely as the square of u varies, and v = 10 when u = 5, find:
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Question No. 18
Given: r varies inversely as the square root of t varies. Write the relationship between r and t, including the constant of proportionality.
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Question No. 19
If r is 4 when t = 9:
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Question No. 20
If x varies inversely as the square root of y varies, and x = 1 when y = 4:
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Question No. 21
Given that a is inversely proportional to b, find the values of x and y in the table (b: 7, x, 11; a: 99, 77, y).
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Question No. 22
Quantity y is inversely related to x. Given that y = 20 when x = 2, find:
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Question No. 23
Given that y varies inversely as the square root of x varies, and y = 40 when x = ½, find:
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Question No. 24
If x varies inversely as the square root of y varies, and x = 2 when y = 9, find:
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Question No. 25
Given that y is inversely proportional to x + 8, find:
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Question No. 26
Given that z is inversely proportional to the square of (p − 12), find:
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Question No. 27
If p ∝ 1/√q and q = 25 when p = 2, find the value of q when p = 100.
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Question No. 28
If y varies inversely as the cube of x varies, and y = 2 when x = 2, find the value of y when x = 4.
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Question No. 29
Given that y varies inversely as the cube of (a + 3) varies, and y = 2 when a = 1, find the value of y when a = 4.
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Question No. 30
P ∝ QR when Q = 4, R = 9 and P = 6.
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Question No. 31
If A, B and C are related so that A ∝ B²/C, and A = 36 when B = 3 and C = 4, calculate B when A = 200 and C = 2.
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Question No. 32
M varies directly with N and inversely with P. M = 3 when N = 240 and P = 40.
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Question No. 33
A varies jointly with B and √C. When A = −18, B = 2 and C = 9, find B when A = 10 and C = 4.
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Question No. 34
The volume of wood in a tree V varies directly with height h and inversely with the square of circumference c. If V = 144 m³ when h = 20 m and c = 1.5 m, find the height h when V = 1 000 m³ and c = 2 m. Write the answer to the nearest metre.
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Question No. 35
M varies directly with N and inversely with P². If M = 8 when N = 6 and P = 3, express M in terms of N and P.
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Question No. 36
The quantity n is partly constant and partly varies with m². Given that n = 11 when m = 1 and n = 5m when m = 2, find n when m = 4.
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Question No. 37
The resistance r to the movement of a vehicle is partly constant and partly proportional to v². If r = 350 N when v = 50 km/h and r = 190 N when v = 30 km/h, find the speed v that gives r = 302.5 N.
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Question No. 38
The Afolabi family receives a monthly electricity bill C. When E = 500 kW, C = ₦7 420; when E = 600 kW, C = ₦7 604.
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Question No. 39
The cost of running a business is partly constant and partly varies with the number of employees. If the cost is ₦28 295 for 60 employees and ₦32 495 for 75 employees, find the cost for 80 employees.