1.甲的期望值=0.2×20+0.6×10十0.2×5=11乙=0.2*30+0.6*10+0.2*-5=112.甲标准差=((20-11)*2*0.2+(10-11)*2*0.6+(5-11)*2*0.2)*1/2=4.9乙标准差=((30-11)*2*0.2+(10-11)*2*0.6+(-5-11)*2*0.2)*1/2=11.14