Rab=0.24 Rac=0.28 Rbc=0.20 ΔR=(Rac-Rbc)/Rp*100% Rp=(Rab+Rbc+Rac)/3=(0.24+0.28+0.20)/3=0.24 (0.28-0.20)/0.24*100%=33%
（0.72/3-0.24）/（0.72/3）
