標題:
F.2 Maths rate and ratio
發問:
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Two alloys X and Y are made up of copper and zinc. Alloy X contains 37% copper whiles alloy Y contains 50% copper. (a) A new alloy is to be made by mixing x kg of alloy X and y kg of alloy Y. Finding the ratio of x : y such that the ratio of copper : zinc of new alloy is at least 2 : 3.
最佳解答:
The amount of copper in the new alloy: 0.37 x + 0.5 y The amount of zinc in the new alloy: (1 - 0.37) x + (1 - 0.5) y = 0.63 x + 0.5 y Now, the required copper : zinc ratio in the new alloy is 2:3, hence: (0.37 x + 0.5 y) / (0.63 x + 0.5 y) = 2 / 3 3 (0.37 x + 0.5 y) = 2 (0.63 x + 0.5 y) 1.11 x + 1.5 y = 1.26 x + y 0.5 y = 0.15 x x / y = 0.5 / 0.15 x / y = 10 / 3 Therefore, the ratio of x : y is 10:3
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