Question

Имеется кусок сплава меди с оловом массой 12 кг. ,содержащий 45 % меди. Сколько чистого олова надо прибавить к этому куску сплава ,чтобы новый сплав содержал 40% меди?

Answer 1

1. 12*0,45=5,4(кг) - вес меди в сплаве

2. х кг- вес добавленного чистого олова, 12+х- новый вес сплава, тогда 

0,4*(12+х)= 5,4

0,4х=0,6

х=1,5

Проверка 13,5 новый вес сплава, 13,5*0,4(40 процентов от веса)=5,4(кг) вес меди в сплаве

Answer 2

12*45/40=13.5    13.5-12=1.5 кг олова

Answer 3

Calculation of the Amount of Pure Lead Needed

To determine the amount of pure lead that needs to be added to the copper-lead alloy to achieve a new alloy with a 40% copper content, we can use the following steps:

1. Calculate the mass of copper in the original alloy: - The original alloy has a mass of 12 kg and contains 45% copper. - Therefore, the mass of copper in the original alloy is 12 kg * 45% = 5.4 kg.

2. Calculate the mass of the remaining elements (lead) in the original alloy: - Since the original alloy contains only copper and lead, the mass of lead can be calculated by subtracting the mass of copper from the total mass of the alloy: - Mass of lead = Total mass of alloy - Mass of copper = 12 kg - 5.4 kg = 6.6 kg.

3. Calculate the mass of the new alloy: - The new alloy is desired to have a copper content of 40%. - Therefore, the mass of the new alloy can be calculated by dividing the mass of copper in the new alloy by the desired copper content: - Mass of new alloy = Mass of copper / Desired copper content = 5.4 kg / 40% = 13.5 kg.

4. Calculate the mass of lead needed to achieve the desired copper content in the new alloy: - The mass of lead needed can be calculated by subtracting the mass of copper in the new alloy from the total mass of the new alloy: - Mass of lead needed = Mass of new alloy - Mass of copper in new alloy = 13.5 kg - 5.4 kg = 8.1 kg.

Therefore, 8.1 kg of pure lead needs to be added to the copper-lead alloy to achieve a new alloy with a 40% copper content.