Sterling Silver is 92.5% pure silver. How many grams of Sterling Silver must be mixed to a 90% Silver alloy to obtain a 500g of a 91% Silver alloy?
Choose the correct choice from the following options:
A) 200
B) 300
C) 400
D) 500
E) 600
Let x and y be the weights, in grams, of sterling silver and of the 90% alloy to make the 500 grams at 91%. Hence   x + y =500   The number of grams of pure silver in x plus the number of grams of pure silver in y is equal to the number of grams of pure silver in the 500 grams. The pure silver is given in percentage forms. Hence   92.5% x + 90% y = 91% 500   Substitute y by 500 - x in the last equation to write   92.5% x + 90% (500 - x) = 91% 500   Simplify and solve   92.5 x + 45000 - 90 x = 45500   x = 200 grams.   200 grams of Sterling Silver is needed to make the 91% alloy.   200nswer 200
<result>A</result>
Sterling Silver is 92.5% pure silver. How many grams of Sterling Silver must be mixed to a 90% Silver alloy to obtain a 500g of a 91% Silver alloy?