Single correct option
The average marks scored by 25 students in a class is 70. If the average marks of the top 10 scorers is 82, what is the average marks of the remaining 15 students?
- A. 58
- B. 60
- C. 62
- D. 64
Show answer and solution
Answer: (C) 62
Total marks of all 25 students = 25 × 70 = 1,750.
Marks of the top 10 = 10 × 82 = 820.
Marks of the remaining 15 = 1,750 − 820 = 930.
Average of the remaining 15 = 930/15 = 62.
Tip: When a group is split into two known-size parts, work entirely with totals (average × count), not with the averages directly — averages don't combine by simple arithmetic.
Marks of the top 10 = 10 × 82 = 820.
Marks of the remaining 15 = 1,750 − 820 = 930.
Average of the remaining 15 = 930/15 = 62.
Tip: When a group is split into two known-size parts, work entirely with totals (average × count), not with the averages directly — averages don't combine by simple arithmetic.
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