The arithmetic mean of the scores of a group of students…

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The arithmetic mean of the scores of a group of students in a test was 52. The brightest 20% of them secured a mean score of 80 and the dullest 25% a mean score of 31. The mean score of remaining 55% is-

  1. A. 45
  2. B. 50
  3. C. 51.4 approx
  4. D. 54.6 approx

Answer: Option C

Here is complete explanation of The arithmetic mean of the scores of a group of students….

Solution(By ExamCraze Team)

Let the required mean score be x
Then,
$$eqalign{ & 20 times 80 + 25 times 31 + 55 times x = 52 times 100 cr & Leftrightarrow 1600 + 775 + 55x = 5200 cr & Leftrightarrow 55x = 2825 cr & Leftrightarrow x = frac{{2825}}{{55}} approx 51.4 cr} $$

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