nguoi ta tha mot qua cau khong tham nuoc vao 1 binh chua day nuoc thi m ca binh tang them 3.4kg con neu tha vaomot binh day dau thi nm ca binh tang them 3.8kg biet Dnuoc =1000kg/m3,cua dau la 800kg/m3. Xac dinh m,V,D cua qua cau.Biet rang ca 2 truong hop qua cau deu chim hoan toan