A silversmith mixed 15g of a 60% silver alloy with 70g of a 25% silver alloy. What is the percent concentration of the resulting alloy?

Answer 1

You need to calculate a weighted average of the concentrations. If the new concentration is x, then

x = [15 / (15 + 70)] (60%) + [70 / (15 + 70)] (25%) = [15(60%) + 70(25%)] / 85

x = 31.2%