7 liters of a 22 percent solution of alcohol in water are mixed with 3 liters of an 11 percent alcohol in water solution. What is the percentage of alcohol in the new solution?
Choose the correct choice.
A) 17.5 %  B) 17.8 %  C) 18.1 %  D) 18.4 %  E) 18.7 %

Rationale: "the total amount of alcohol is 0.22 ( 7 ) + 0.11 ( 3 ) = 1.87 liters . the percentage is 1.87 / 10 = 18.7 / 100 which is 18.7 % the answer is e ."
Answer: E