The average marks of a class of 35 students is 45 and that of another class of 55 students is 65. Find the average marks of all the students?
Choose the correct choice from the following options.
A) 52.6	B) 52.4	C) 52.1	D) 57	E) 52.9

Rationale: "sum of the marks for the class of 35 students = 35 * 45 = 1575 sum of the marks for the class of 55 students = 55 * 65 = 3575 sum of the marks for the class of 90 students = 1575 + 3575 = 5150 average marks of all the students = 5150 / 90 = 57 . answer : d"
Answer: D