Question

Ребят помогите башка трещит .Решите задачу. Имеется кусок сплава меди и олова массой 15 кг,содержащий 20% меди. Сколько чистой меди надо добавить к этому сплаву,чтобы сплав содержал 40% олова .

Answer 1

X + y = 15
0,2x + y = 0,4( X + y )
y = ?
Решение
0,2х + y = 0,4x + 0,4y
0,4x - 0,2x = y - 0,4y
0,2x = 0,6y
2x = 6y
X = 3y
X + y = 15
3y + y = 15
4y = 15
y = 3,75 ( кг )
Ответ 3,75 кг

Answer 2

Problem Analysis

To solve this problem, we need to determine how much pure copper needs to be added to a 15 kg alloy of copper and tin to make the alloy contain 40% tin.

Solution

Let's break down the problem step by step:

1. Calculate the mass of copper in the initial alloy: - The initial alloy has a mass of 15 kg and contains 20% copper. - To find the mass of copper, we multiply the total mass by the percentage of copper: 15 kg * 0.20 = 3 kg of copper.

2. Calculate the mass of tin in the initial alloy: - Since the alloy contains 20% copper, the remaining 80% must be tin. - To find the mass of tin, we multiply the total mass by the percentage of tin: 15 kg * 0.80 = 12 kg of tin.

3. Calculate the mass of tin required in the final alloy: - The final alloy should contain 40% tin. - We can calculate the total mass of the final alloy using the formula: mass of tin / (percentage of tin / 100) = 12 kg / (40 / 100) = 30 kg.

4. Calculate the mass of copper required to achieve the desired tin percentage: - The total mass of the final alloy is 30 kg, and we already have 15 kg of the initial alloy. - To find the mass of copper required, we subtract the mass of the initial alloy from the total mass of the final alloy: 30 kg - 15 kg = 15 kg of copper.

Therefore, 15 kg of pure copper needs to be added to the initial alloy to make the final alloy contain 40% tin.

Conclusion

To make the alloy contain 40% tin, you would need to add 15 kg of pure copper to the initial alloy.