E=32P\rm{E=\dfrac{3}{2} P}E=23P
E=23P\rm{E=\dfrac{2}{3} P}E=32P
E=12×32P\rm{E=\dfrac{1}{2} \times \dfrac{3}{2} P}E=21×23P
E=12×23P\rm{E=\dfrac{1}{2} \times \dfrac{2}{3} P}E=21×32P