The average (arithmetic mean) of all scores on a certain algebra test was 90. If the average of the 8 male students’ grades was 83, and the average of the female students’ grades was 92, how many female students took the test?	Choose the most appropriate option
A) 8 B) 9 C) 10 D) 21 E) 28
Total Marks of male = M   Total Marks of female = F   Number of males = 8   Number of females = f   Given: (M+F)/(8+f) = 90 -------------1   Also given, M/8 = 83 Thus M = 664 ---------2   Also, F/f = 92 thus F = 92 F - --------3   Put 2 and 3 in 1: we get   (664+92f)/(8+f) = 90   solving this we get f = 28   Ans: 28
<result>E</result>
The average (arithmetic mean) of all scores on a certain algebra test was 90. If the average of the 8 male students’ grades was 83, and the average of the female students’ grades was 92, how many female students took the test?