Question

There are 30 students in a year 10 maths class. In the latest test the 21 girls in the class score a mean of 61%. In the same test the 9 boys in the class scored a mean of 78%. Calculate the mean for the whole group of students.

Answer 1

Total score of the 21 girls = 61*21 = 1281 
Total score of 9 boys = 78*9 = 702

Mean for all 30 students  = (1281+702) / 30 =  1983 / 30 = 66.1 %  (answer)