Question

A class consist of 50 students out of which 30 are girl the mean marks scored by girls in a test 73 ( out of 100) and that of boy is 71 ( out of 100) determine the mean s
core of whole class

Answer 1

let g1,g2....g30 are girls and b1,b2.....b20 are boys then
(g1+g2+....+g30)/30=73
g1+g2+.....+g30=73*30
(b1+b2+....+b20)/20=71
b1+b2+.....+b20=71*20
now mean score of total class is
(g1+g2+...g30+b1+b2+......b20)/50
(73*30+71*20)/50
(73*3+71*2)/5
(219+142)/5
361/5
72.2