Question

An alloy is a mixture of metals. Suppose that a certain alloy is made by mixing 50 grams of an alloy that 52% copper with 78 grams of pure copper. How many grams of copper are in the resulting mixture? What percent of the resulting mixture is copper?

Answer 1

See below in bold.

Explanation:

The 50 grams of alloy contains 50 * 0.52 = 26 g of pure copper.

So the amount of copper n the mixture = 78 + 26 = 104 g.

The total mass of the mixture = 78 + 50 = 128 g.

% copper = 104 * 100 / 128

= 81.25%.