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
(a) 45 (b) 50 (c) 51.4 approx. (d) 54.6 approx.
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
(a) 45 (b) 50 (c) 51.4 approx. (d) 54.6 approx.