If 25% of a class averages 80% on a test, 50% of the class averages 65% on the test, and the remainder of the class averages 90% on the test, what is the overall class average? Pick one:  A) 60 %  B) 65 %  C) 70 %  D) 75 %  E) 80 %

Rationale: "this question is a weighted average question with a series of dependent variables . the remaining portion of the class represents 100 % - 25 % - 50 % = 25 % of the class converting the portions of the class population to decimal weights , we find : class average = 0.25 x 80 + 0.50 x 65 + 0.25 x 90 = 75 the class average is 75 % final answer d ) 75 %"
Answer: D