Multiple choice

The average of 15 papers is 50. The average of the first 8 papers is 48 and of the last eight papers is 54. Find the marks obtained in the 8th paper.

  1. 66

  2. 64

  3. 58

  4. 56
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A Correct answer
Explanation

Sum of 15 papers = 15 * 50 = 750. Sum of first 8 = 8 * 48 = 384. Sum of last 8 = 8 * 54 = 432. The 8th paper is counted twice: (384 + 432) - 750 = 816 - 750 = 66.

AI explanation

The total marks for all 15 papers is 15 multiplied by 50, which equals 750. The total for the first 8 papers is 8 multiplied by 48, equaling 384, and the total for the last 8 papers is 8 multiplied by 54, equaling 432. If you add the totals of the first 8 and last 8 papers, you get 384 plus 432, which equals 816. Since there are only 15 papers, the 8th paper has been counted twice, so its score is the difference between this sum and the total score, which is 816 minus 750, resulting in 66.

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