If 15 students in a class average 75% on an exam and 10 students average 95% on the same exam, what is the average in percent for all 25 students? Options
A) 81 %  B) 82 %  C) 83 %  D) 84 %  E) 85 %

Rationale: "( 15 * 75 + 10 * 95 ) / 25 = 83 % the answer is c ."
Answer: C