Question

Сделайте систему уравнения.Кусок сплава меди и цинка массой в 36 кг содержит 45% меди. Какую массу меди нужно добавить к этому куску, чтобы полученный новый сплав содержал 60 % меди?

Answer 1

Меди в сплаве будет  36*0,45=16,2 кг
Тогда цинка будет 36-16,2=19,8 кг, что будет составлять 100-60=40% в новом сплаве.
Значит вес нового сплава равен $\frac{19,8\cdot 100}{40}=49,5$ кг
Добавить надо будет меди  49,5-36=13,5 кг.

Answer 2

Problem Analysis

We are given a piece of alloy containing copper and zinc with a total mass of 36 kg. The alloy currently contains 45% copper. We need to determine the mass of copper that needs to be added to the alloy in order to obtain a new alloy with 60% copper.

Solution

Let's assume the mass of copper to be added is x kg. Since the total mass of the alloy is 36 kg, the mass of zinc in the alloy is (36 - x) kg.

We can set up the following equation based on the percentage of copper in the alloy:

0.45 * 36 + x = 0.60 * (36 + x)

Simplifying the equation:

16.2 + x = 21.6 + 0.60x

Solving for x:

0.40x = 5.4

x = 5.4 / 0.40

x = 13.5

Therefore, we need to add 13.5 kg of copper to the alloy in order to obtain a new alloy with 60% copper.

Answer

To obtain a new alloy with 60% copper, 13.5 kg of copper needs to be added to the existing alloy.