(m*(1-p)+2m*(1+p)) / (m*(1-p)^2+2m*(1+p)^2)
p=10%时: (m*0.9+2m*1.1)/(m*0.81+2m*1.21)=3.1m/3.23m=310/323≈0.96%
解:二月份A,B两种产品的销售总额的比:(1-10%)m::(1+10)×2m=0.9:2.2=9:22=0.41
三月份A,B两种产品的销售总额的比:(1-10%)×9m::(1+10)×22m=8.1:24.2=81:242=0.33
一月:A m B 2m
二月:A m(1-p) B 2m(1+p) 总额:3m+mp
三月:A m(1-p)2 B 2m(1+p)2 总额:3mp2+2mp+3m
二月三月总额比:原式=3+p/3p2+2p+3
当p=0.1时,比值精确值=0.85