Mathematics Higher Level Robert Joinson

©Sumbooks2002Higher Level17. Direct and Inverse Proportion1) y varies directly as x and y = 4 when x = 6.a) Find an expression for y in terms of x. b) Calculate the value of y when x = 8.c) Calculate the value of x when y = 15.2) If v varies directly as r 3 and v = 24 when r = 2 find the value of v when r = 3.3) y is directly proportional to √x and x = 9 when y = 2.a) Find an expression for y in terms of x. b) Find the value of y when x = 4.c) Calculate the value of x when y = 6.4) a varies directly as b 3 . If a = 32 when b = 2 find a when b = 4.5) Given that y is inversely proportional to the square of x, and y is equal to 0.75 when x = 2.a) Find an expression for y in terms of x.1b) Calculate y when x = 3. c) Calculate x when y = ----- .126) y varies inversely as x. If y = 1.5 when x = 2 find y when x = 4.7) y is proportional to the cube root of x . y = 10 when x = 8.a) Find an expression for y in terms of x.b) Calculate (i) y when x = 64. (ii) x when y = 25.8) y varies inversely as x 2 . Copy and complete the following table.x 1 2 3 4y 0.759) a varies directly as the square root of b. If a = 1 when b = 9 find a when b = 4.10) y varies directly as the cube root of x. Copy and complete the following table.x 0.125 1 8 64y 111) The table below shows values of y for values of the variable x, which are linked by theequation y = 8x n .x 0.5 1 2y 1 8 64Find (a) The value of n. (b) y when x = 0.25.12) y varies inversely as the square of x. Copy and complete the table below.x 0.5 0.75 1 1.5y 6