Posted by preston on Thursday, October 2, 2008 at 4:33pm.
Since the mean score of the 42 students was 75.5, the sum of all the scores of all students was 75.5(42)
let the number of students who passed be x
then 42-x must have failed
the sum of the scores of the passing students is then 81x, and
the sum of the scores of the failing students was (42-x)(60)
so isn't 81x + (42-x)(60) = (42)(75.5) ???
Take it from there
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