mixture problem

Question

A metal alloy weighing 8 oz and containing 30% platinum is melted and mixed with 2 oz of pure platinum. What percent of the resulting alloy is platinum?

Answer 1

30% of 8 oz = 0.30 x 8 = 2.4 oz of platinum

2.4 oz + 2 oz = 4.4 oz of platinum

Total weight = 8 oz + 2 oz = 10 oz

% platinum = 4.4 oz platinum/10 oz total (x100) = 44% platinum