A school has 4 section of Chemistry in Class X having 60, 35, 45 and 42 students. The mean marks obtained in Chemistry test are 50, 60, 55 and 45 respectively for the 4 sections. Determine the overall average of marks per student.  Select
A) 50  B) 52  C) 51  D) 53  E) none of the above

Rationale: "required average marks = 60 ã — 50 + 35 ã — 60 + 45 ã — 55 + 42 ã — 45 / 60 + 35 + 45 + 42 = 3000 + 2100 + 2475 + 1890 / 182 = 9465 â  „ 182 = 52 answer b"
Answer: B