A metal alloy weighing 12 lb. and containing 60% platinum is melted and mixed with 8 lb. of a different alloy which contains 20% platinum. What percent of the resulting alloy is platinum?
total amount of platinum = 0.6*12 + 0.2*8 = 8.8 lb.
total alloy = 12 + 8 = 20 lb.
percentage platinum = 100*8.8/20 = 44%
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