Question 943189
a gold merchant has some 12 carat gold (12/24 pure gold) and some 22 caret gold ( 22/24 pure gold). How many grams of each could be mixed to get 25 grams of 15 carat gold?
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Note:: 15 carat gold is 0.625 = 15/24 pure gold
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Quantity Eq:: t + w = 25 grams
Gold Eq::::(12/24)t + (22/24)w = (15/24)*25
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Modify for elimination::
12t + 12w = 12*25
12t + 22w = 15*25
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Subtract and solve for "w"::
10w = 3*25
w = 7.5 grams (amt. of 22 carat gold needed)
Solve for "t":
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t = 25-w = 17.5 grams (amt. of 12 carat gold needed)
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Cheers,
Stan H.
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