(3)A=57;B=2400(或2399.63);C=0.4;D=60.59% 说明:A=100×0.3+60×0.4+10×0.3=57 B=(200-140)2×0.4+(100-140)2×0.6+(0-140)2×0=2400 或B=(140×34.99%)2=2399.63 C=1-0.4-0.2=0.4 D=96.95/160×100%=60.59%

(3)A=57;B=2400(或2399.63);C=0.4;D=60.59% 说明:A=100×0.3+60×0.4+10×0.3=57 B=(200-140)2×0.4+(100-140)2×0.6+(0-140)2×0=2400 或B=(140×34.99%)2=2399.63 C=1-0.4-0.2=0.4 D=96.95/160×100%=60.59%