Statistics Part 1

Given that, total students =100
and number of boys =70
∴‌‌ No. of girls =100−70=30
Average of 100 students =72
∴ Total marks of 100 students =100×72=7200
Average of 70 boys =75
∴ Total marks of 70 boys =70×75=5250
∴ Total marks of 30 girls =7200−5250=1950
∴ Average marks of 30 girls =‌

1950

30

=65