Multiple choice

The average of 13 papers is 50. The average of the first 7 papers is 42 and that of the last 7 papers is 35. What is the marks of the 7th paper?

  1. 33

  2. 104

  3. 113

  4. 54

  5. None of these
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Sum of 13 papers = 13 × 50 = 650. Sum of first 7 = 7 × 42 = 294. Sum of last 7 = 7 × 35 = 245. The 7th paper is counted in both groups, so: 294 + 245 - 7th paper = 650 → 7th paper = 294 + 245 - 650 = -111. This is impossible, so 'None of these' is correct.

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