对于这组数据：27 23.9 41.6 33.1 40.6 18.8 13.7 28.9 13.2 14.5 27.0 34.8 28.9 3.2 50.1 5.6
期望：E(x)=(27+23.9+41.6+33.1+40.6+18.8+13.7+28.9+13.2+14.5+27.0+34.8+28.9+3.2+50.1+5.6)/16=22.175
方差：D(x)=(27-E(x))^2*(1/16)+(23.9-E(x))^2*(1/16)+(41.6-E(x))^2*(1/16)+(33.1-E(x))^2*(1/16)+(40.6-E(x))^2*(1/16)+(18.8-E(x))^2*(1/16)+(13.7-E(x))^2*(1/16)+(28.9-E(x))^2*(1/16)+(13.2-E(x))^2*(1/16)+(14.5-E(x))^2*(1/16)+(27-E(x))^2*(1/16)+(34.8-E(x))^2*(1/16)+(28.9-E(x))^2*(1/16)+(3.2-E(x))^2*(1/16))+(50.1-E(x))^2*(1/16))+(5.6-E(x))^2*(1/16)==173.3
标准差=把D(x)开二次根号=13.1644
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说明：这是此组：8.7 15.2 7.1 5.2 16.5 13.8 19.2 11.2 15.7 10.0 5.6 1.5 33.8 9.2的标准差
期望：E(x)=(8.7+15.2+7.1+5.2+16.5+13,8+19.2+11.2+15.7+10.0+5.6+1.5+33.*+9.2)/10=13.335961
方差：D(x)=(8.7-E(x))^2*(1/14)+(15.2-E(x))^2*(1/14)+(7.1-E(x))^2*(1/14)+(5.2-E(x))^2*(1/14)+(16.5-E(x))^2*(1/14)+(13.8-E(x))^2*(1/14)+(19.2-E(x))^2*(1/14)+(11.2-E(x))^2*(1/14)+(15.7-E(x))^2*(1/14)+(10.0-E(x))^2*(1/14)+(5.6-E(x))^2*(1/14)+(1.5-E(x))^2*(1/14)+(33.8-E(x))^2*(1/14)+(9.2-E(x))^2*(1/14)=58.4120
标准差=把D(x)开二次根号=7.643