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

*Hint: In order to solve this equation and make it easier for you, you must use proportions and figure out how many quarts there is in 10% of antifreeze solution.

The reason you need to find it for 10% is because only 10% is needed in order for the solution to reach 40%.

12/30 = x/10
2/5 = x/10
4 = x

The answer would be 4 quarts.