Question

the average age of 40girls is reduced by one year, when 10 girls whose average age is 20 years are replaced by 10 new girls. the average age of new comers is?

Answer 1

let, average age of 40 girls = x

so, total = 40x

agan say, average age of 10 girls = y

so, total= 10y

ATQ,

40x-200+10y=40(x-1)

or, y=16.