Question

The capacity of an automobile cooling system is 16 quarts. It is half full of a 15% antifreeze solution. The owner is adding 2 gallons of a 90% solution (remember, 1 gallon = 4 quarts). When he is finished, what will the solution's percentage value be?

Answer 1

15% of 8quarts and 90% of 8 quarts = x% of 16 quarts 0.15 x 8 quarts + 0.90 x 8 quarts =1.2 quarts + 7.2 quarts = 8.4 quarts 8.4 quarts/16 quarts = (8.4)/(16) = 0.525 = 52.5% ONLY because the solutions are 50-50 we could have averaged the percentages (15 + 90)/2 = 52.5