Question

Sterling silver is an alloy of silver that is 92.5% pure silver. If x grams

of sterling silver are mixed with y grams of an 88% silver alloy to produce a 91% silver
alloy, which of the following equations correctly relates x and y?
A. 0.075x+0.12y = 0
B. 0.015x -0.03y = 0
C. 0.925x +0.88y = 91
D. 0.925x +0.88y = 0.91xy

Answer 1

The correct answer is actually B

Answer 2

D. 0.925x + 0.88y = 0.91(x + y)

Explanation:

The important point to remember is that the total mass of pure silver is the same on each side of the equation.

0.925x = mass of pure silver in first alloy

0.88 y = mass of pure silver in second alloy

The final alloy has a mass of (x + y) g and is 91 % pure silver, so

0.925x + 0.88y = 0.91(x + y)