A 40-liter solution of alcohol and water is 5 percent alcohol. If 5.5 liters of alcohol and 4.5 liters of water are added to this solution, what percent of the solution produced is alcohol?  Pick one.
A) 9 %
B) 11 %
C) 13 %
D) 15 %
E) 17 %

Rationale: "the percent of alcohol in the solution is ( 0.05 ( 40 ) + 5.5 ) / 50 = 7.5 / 50 = 15 % the answer is d ."
Answer: D