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標題:

F.3 Maths(Percentage)

發問:

An alloy A contains 35% of zinc by weight. Some alloy A and pure zinc are melted to form a new alloy that weights 400kg and contains 1057/16 % of zinc. What are the weights of alloy A and zinc needed respectively to form the new alloy? (Give your answers correct to the nearest kg.)

最佳解答:

Let there are x kg and y kg of the mass of alloy A and the mass of pure zinc needed to form the new alloy respectively. x + y = 400 -------------------------------------(1) 0.35x + y = 400 (1057/16)% ------------------(2) (2), 0.35x + y = 400 (66.0625%) ----------(3) (1) – (3), x + y – (0.35x + y) = 400 – 400(66.0625%) 0.65x = 400 – 264.25 0.65x = 400 – 264.25 0.65x = 135.75 x = 208.846 Sub x = 208.846 into (1), 208.846 + y = 400 y = 191.154 ∴ The weights of alloy A needed to form the new alloy is 209 kg . ∴ The weights of zinc needed to form the new alloy is 191 kg . 希望幫到您！

其他解答:

Let there are x kg and y kg of the mass of alloy A and the mass of pure zinc needed to form the new alloy respectively. x + y = 400 -------------------------------------(1) 0.35x + y = 400 (1057/16)% ------------------(2) (2), 0.35x + y = 400 (66.0625%) ----------(3) (1) – (3), x + y – (0.35x + y) = 400 – 400(66.0625%) 0.65x = 400 – 264.25 0.65x = 400 – 264.25 0.65x = 135.75 x = 208.846 Sub x = 208.846 into (1), 208.846 + y = 400 y = 191.154 ∴ The weights of alloy A needed to form the new alloy is 209 kg . ∴ The weights of zinc needed to form the new alloy is 191 kg I hope I can help you.6A560DB68EC65D60