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Two positive numbers X and Y are inversely proportional. if X increases by 20% then percentage decreases in y is a) 15 b) 16 2/3 c) 17 11/9 d) 25 |
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Answer» x is inversely proportional to y ⇒ x = k/y Make y the SUBJECT: x = k/y xy = k y = k/x When x increases by 20% ⇒ x = 1.2x Sub x = 1.2x into the equation: y = k/1.2x Find the increase in y: increase = k/1.2x - k/x = k/6x Find the PERCENTAGE increase: Percentage increase =(k/6x ÷ k/x) x 100 Percentage increase = 16 2/3% ANSWER: (b) 16 2/3% |
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