2023 · Q20
Average marks in Mathematics of Section A comprising 30 students is 65 and that of Section B comprising 35 students is 70. What are the average marks (approximately) of both the sections if it was detected later that an entry of 47 marks was wrongly made as 74?
Elementary MathematicsStatistics
- A67.28
- B67.58
- C68.11
- D68.63
Explanation
The section totals are 30 × 65 = 1950 and 35 × 70 = 2450, summing to 4400 over 65 students. Correcting the entry 74 → 47 reduces the total by 27 to 4373. The corrected average is 4373/65 ≈ 67.28 (A).