If 15 students in a class average 73% on an exam and 10 students average 88% on the same exam, what is the average in percent for all 25 students? Choose the correct choice from the following:
A) 77 %
B) 78 %
C) 79 %
D) 80 %
E) 81 %

Rationale: "( 15 * 73 + 10 * 88 ) / 25 = 79 % the answer is c ."
Answer: C