40 g of copper was added to a 600 g weld containing 20% copper. What was the percentage of copper in the new alloy?

| January 30, 2021 | education

1) Determine how much copper is contained in 600 g of the alloy, for this we will use the rule for finding the percentage of the number: in order to find the percentage of the number, you need to multiply the number by the fraction that is the given percentage, that is:

600 * 20/100 = 120 (g) – contains copper in 600 g of the alloy.

2) Determine what weight of the alloy will become after 40 g of copper is added to it:

600 + 40 = 640 (g) – weight of the alloy.

3) Determine the weight of copper in the alloy:

120 + 40 = 160 (g).

4) Determine what percentage is copper from the alloy, for this we use the rule: to find how many percent one number is from another, it is necessary to divide one number by another and multiply the result by 100%, that is:

160: 640 * 100 = 25% – is copper in a new alloy.

Answer: 25%.



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.