"The arithmetic mean of the scores of a group of students in a test was 52. The br
Channel: Doubtnut
Date: 2020-04-12

"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."