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?

48%

Step-by-step explanation:

We calculate the amount of platinum in both.

For the first, we have 60% platinum in 12lb. Amount of platinum here is 60/100 * 12 = 7.2lb

For the second, we have 20% platinum in 8lb = 20/100 * 12 = 2.4lb

Total weight of the new alloy is 12lb + 8lb = 20lb

Total weight of platinum is 2.4lb + 7.2lb = 9.6lb

Percentage of platinum present is thus 9.6/20 * 100 = 48% platinum

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