1.Mot khoi sat co khoi luong 390000g
a)Tinh the tich cua khoi sat
b)Mot khoi thuy tinh co the tich lon gap 2 lan the tich khoi sat.Hoi khoi nao co khoi luong lon hon va lon hon bao nhieu lan?
Biet khoi luong rieng cua sat la 7800kg/m3 va khoi luong rieng cua khoi thuy tinh la 2500kg/m3