SOLUTION: A certain grade of gun metal ( a mixture of tin & copper ) contains 16% tin. How much tin must be added to make a mixture that is 18% tin.

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Question 1043069: A certain grade of gun metal ( a mixture of tin & copper ) contains 16% tin. How much tin must be added to make a mixture that is 18% tin.
Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
w amount of gunmetal;
add x amount of tin;

%280.16w%2Bx%29%2F%28w%2Bx%29=0.18

0.16w%2Bx=0.18%28w%2Bx%29

0.16w%2Bx=0.18w%2B0.18x

x-0.18x=0.02w

0.82x=0.02w

82x=2w

highlight%28x=w%2F41%29-----This is the correct answer for the problem description presented as posted.

If started with 100 grams of gunmetal at 16% tin, amount of tin to add would be 100%2F41 or about 2.44 grams of tin.