A school has 4 section of Chemistry in Class X having 70, 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.
Choose the most appropriate option
A) 50.9 B) 52.9 C) 51.9 D) 53.25 E) none of the above

Rationale: "required average marks = 70 ã — 50 + 35 ã — 60 + 45 ã — 55 + 42 ã — 45 / 70 + 35 + 45 + 42 = 3500 + 2100 + 2475 + 1890 / 192 = 9965 â  „ 192 = 51.90 answer c"
Answer: C