Question

A Mathematics test was taken by 4 boys and 6 girls. The mean marks of the 10 students was 49.

a) Calculate the total marks obtained by 10 students.
b) If the mean marks of 6 girls was 51, calculate the mean marks of 4 boys.

Answer 1

Total population/Total number of observations = 10(boys+girls)

a.) Combined mean = Total marks/Total population 
49 = Total marks/10
∴ Total marks = 490 

b.) Mean marks of girls is 51. Let m be the mean marks of boys.

Therefore, 
Combined mean =
[mean marks of girls×(number of girls) + mean marks of boys×(number of boys)]/Total population
49= [51(6)+m(4)]/10
49×10= 51(6)+4m
4m = 184
m=46