<PRE><B>Question 937738</B>
A metal alloy weighing 9 lb. and containing 75% copper is melted and mixed with 11 lb. of a different alloy which contains 15% copper. What percent of the resulting alloy is copper? 
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Equation:
copper + copper = copper
0.75*9 + 0.15*11 = x*20 lb
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75*9 + 15*11 = x*2000
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x = (675 + 161)/2000
x = 41.8% (percent of copper in the final mix)
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Cheers,
Stan H.
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