Question

An automobile's radiator has a capacity of fifteen quarts, and it currently contains twelve quarts of a thirty percent antifreeze solution. How many quarts of pure antifreeze must be added to strengthen the solution to forty percent?



2 quarts
3 quarts
4 quarts

Answer 1

the whole capacity itself is only 15 Qts and it already has 12 quarts so 4 quarts is eliminated. 30% antifreeze means 70% water. out if 12 quarts 30% is antifreeze. which is 3.6 quarts. Say you add x amount of antifreeze to make it 40% antifreeze. So you can set up ratio as follows = The total antifreeze after addition will be 3.6 + x. and the total mixture will be 12 + x. Now (3.6 + x) / (12 + x) = 40/100. Now after simplifying you get 2 quarts. as your answer.