The average marks of a class of 25 students is 50 and that of another class of 40 students is 65. Find the average marks of all the students?  Choose the correct choice from the following answers.
A) 52.6 B) 52.4 C) 52.1 D) 59 E) 52.9

Rationale: "sum of the marks for the class of 25 students = 25 * 50 = 1250 sum of the marks for the class of 40 students = 40 * 65 = 2600 sum of the marks for the class of 65 students = 1250 + 2600 = 3850 average marks of all the students = 4850 / 65 = 59 . answer : d"
Answer: D