pb=Ga+Gb/Sb=ρagaha+ρbgbhb/Sbpb'=Ga+Gb/Sa=ρagaha+ρbgbhb/Sa所以Pb:pb'=ρagaha+ρbgbhb/Sb:ρagaha+ρbgbhb/Sa=Sa:Sb=1:4