An alloy is a mixture of metals. Suppose that a certain alloy is made by mixing 50 grams of an alloy that contains 52% copper with 78 grams of pure copper.

An alloy is a mixture of metals. Suppose that a certain alloy is made by mixing 50 grams of an alloy that contains 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?

The original alloy has a mass of 50 grams,

52% of this 50 grams is copper,

mass of copper = 0.52 x 50 = 26 grams

78 grams of pure copper added will bring the mass of copper to..

mass of copper = 26 + 78 = 104 grams of pure copper

After adding 78 grams of copper to the alloy, the resultant mass of the mixture will be = original mass of alloy + mass of the pure copper added

==> 50 + 78 = 128 grams

Percentage of the resulting mixture that is copper = (total mass of copper in the mixture/total mass of mixture x 100%)

==> 104/128 x 100% = 81.25%