I had posted this as a reply to an earlier post, but have not gotten a response. In Chemistry, the Central Science 10th ed, there is a problem regarding % comp by mass with the following information.
An alloy of gold and silver, totalling .675 cm3 volume, 9.85g mass. Density of gold 19.3g/cm3; denisty of silver 10.5 g/cm3. What is the percent of gold by mass. The answer key in the book says 61.5% gold by mass, but doesn't give the process for calculating this. An earlier poster put this problem on the board but the equation received (when I tried it) gave a very different answer.
I can sort of work back from the answer. The problem is working forward, not knowing the answer, if that makes any sense.