Question

if a type of brass is made in the ration 3:7 by zinc and copper and you need 2kg of brass how much grams of zinc do you need?

Answer 1

600g

Explanation:

ratio 3:7 means there are 3 + 7 = 10 PARTs. zinc is 3/10 (30%) and copper is 7/10 (70%).

2kg = 2000g (of brass).

2000/10 = 200 (for one PART).

zinc is 30% (3 parts).

so we need 3 X 200 = 600g of zinc.