Multiple choice

Directions: In the following questions, out of the four alternatives, choose the one which can be substituted for the given words/sentence. 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. 54.6%

  2. 45%

  3. 50%

  4. 51.4%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Take the total number of students as 100. The top 20 contribute 1600 points and the bottom 25 contribute 775 points, leaving 2825 points for the remaining 55 students. Their mean is 2825/55 = 51.4, so the numerical answer matches option D, although the percent sign is inappropriate.

AI explanation

Let the total number of students be 100, making the total marks 5200 since the overall mean is 52. The brightest 20 students scored a mean of 80 for 1600 marks, and the dullest 25 students scored a mean of 31 for 775 marks. The remaining 55 students have 5200 - 1600 - 775 = 2825 marks. Dividing 2825 by 55 gives a mean score of 51.4.

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