In a certain accounting class of 100 students, 70% of the students took the final exam on the assigned day while the rest of the students took the exam on a make-up date. If the students on the assigned day had an average score of 60%, and the students on the make-up date had an average score of 80%, what was the average score for the entire class? Choose the correct choice from the following answers
A) 64 % B) 66 % C) 68 % D) 70 % E) 72 %

Rationale: 70 % of the class scored 60 % and 30 % of the class scored 80 % . the difference between 60 % and 80 % is 20 % . the average will be 60 % + 0.3 ( 20 % ) = 66 % . the answer is b .
Answer: B