There are C girls in a class, and their average height is M inches. In the same class, there are D boys with an average height of N inches. What is the average height of all the students in the class?	Choose the correct answer:
A) (X + Y)/(M + N)  B) (M + N)/(X + Y)  C) (XM + YN)/(M + N)  D) (CM + DN)/(C+ D)  E) MN/XY
Total height = CM+(CM + DN)/(C+N   No of students = C+(CM + DN)/(C+   Avg = (CM+(CM + DN)/(C+N)/(C+(CM + DN)/(C+)   Answer is (CM + DN)/(C+
<result>D</result>
There are C girls in a class, and their average height is M inches. In the same class, there are D boys with an average height of N inches. What is the average height of all the students in the class?