Question

A youth club has 60 members
40 of the members are boys
20 of the members are girls
a mean amount of videos watched last week by all members was 2.8
mean number of videos watched by the boys was 3.3
calculate the mean number of videos watched last week by the 20 girls.
show working out please

Answer 1

60 times 2.8 = 168 videos watched in total 
40 times 3.3 = 132 videos watched by boys 
168 -132 = 36 videos watched by girls 
36 / 20 = 1.8