There are 10 boys and 20 girls in a class. The class has a test. The mean mark for all the class is 60. The mean mark for the girls is 54. Work out the mean mark for the boys.
Mean = Sum of all the numbers/How many numbers there are60=sum of all numbers/30 therefore 1800= sum of all the test scores of class54= sum of all the girls' scores/20 therefore 1080 = sum of all the girl's test scoreTo calculate sum of all the boy's test score 1800-1080 = 720x=720/10 therefore x=72 therefore mean score for boys = 72
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