Given, A family has 3 children. ∴ Sample space ={BBB,BBG,BGB,GBB,GGG,GGB,GBG,BGG} A is the event that family has children of both sexes. ∴A={BBG,BGB,GBB,GGB,GBG,BGG} B be the event that family has atmost one boy. ∴B={GGG,GGB,GBG,BGG} A∩B={GGB,GBG,BGG} P(A)=