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___________?
Q1. 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___________?
Answer: 51.4 approx.
Explanation: Setting up: 0.20×80 + 0.25×31 + 0.55×x = 52. So 16+7.75+0.55x = 52, giving x ≈ 51.4.