Question

К 20 кг латуни сплава меди и цинка добавили 1 кг цинка, после чего содержание цинка в сплаве увеличилось на 3%. Сколько цинка было в сплаве первоначально.Был бы признателен за оперативный ответ. Ребенку спасть пора, а еще английский.

Answer 1

Пусть в первоначальном сплаве Х % цинка, тогда
1) 20*Х/100 кг цинка в первом сплаве
2) 1+0,2*Х кг цинка в новом сплаве
3) 1+20=21 кг вес нового сплава
4) (1+0,2*Х)/21=(Х+3)/100
100*(1+0,2*Х)=21*(Х+3)
100+20*Х=21*Х=63
Х=37

Ответ 37 %

Answer 2

Problem Analysis

We are given that 20 kg of a brass alloy containing copper and zinc had 1 kg of zinc added to it. As a result, the zinc content in the alloy increased by 3%. We need to determine the initial amount of zinc in the alloy before the addition.

Solution

Let's assume the initial amount of zinc in the alloy was x kg.

According to the problem, when 1 kg of zinc was added, the zinc content in the alloy increased by 3%. This means that the new zinc content is 103% of the initial zinc content.

We can set up the following equation to represent this relationship:

x + 1 = 1.03x

Simplifying the equation, we have:

1 = 0.03x

Dividing both sides of the equation by 0.03, we find:

x = 1 / 0.03

Calculating this value, we get:

x ≈ 33.33 kg

Therefore, the initial amount of zinc in the alloy was approximately 33.33 kg.

Answer

The initial amount of zinc in the alloy was approximately 33.33 kg.