A school has 4 section of Chemistry in Class X having 65, 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. Answers.
A) 50.25 B) 52.25 C) 51.95 D) 53.25 E) none of the above

Rationale: required average marks = 65 ã — 50 + 35 ã — 60 + 45 ã — 55 + 42 ã — 45 / 65 + 35 + 45 + 42 = 3250 + 2100 + 2475 + 1890 / 187 = 9715 â  „ 187 = 51.95 answer c
Answer: C