Multiple choice

The arithmetic mean score of a group of students in a test was 60. The 15% of the student's mean score is 85 and the 25% of the student's mean score is 30. The mean score of remaining students is

  1. 66.25

  2. 62.25

  3. 58.25

  4. 60.25
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A Correct answer
Explanation

Let total students be N. Mean = 60. Sum = 60N. 15% of students have mean 85 (sum = 0.15N * 85 = 12.75N). 25% have mean 30 (sum = 0.25N * 30 = 7.5N). Remaining 60% have sum = 60N - 12.75N - 7.5N = 39.75N. Mean of remaining = 39.75N / 0.6N = 66.25.

AI explanation

Let the total number of students be N, so the total sum of scores is 60N. The first 15% of students have a sum of 0.15N * 85 = 12.75N, and the next 25% have a sum of 0.25N * 30 = 7.5N. The remaining 60% of students have a total score of 60N - 12.75N - 7.5N = 39.75N. The mean score of these remaining students is 39.75N divided by 0.60N, which equals 66.25.

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