Question

某次考试10人成绩为:78,88,90,85,84,88,86,80,75,69。方差是多少

Answer 1

问：某次考试10人成绩为:78,88,90,85,84,88,86,80,75,69。方差是多少

答：平均值m=(78+88+90+85+84+88+86+80+75+69)/10=823/10=82.3

问：方差是多少

问：快点啊

答：方差=[(78-82.3)^2+(88-82.3)^2+(90-82.3)^2+(85-82.3)^2+(84-82.3)^2+(88-82.3)^2+(86-82.3)^2+(80-82.3)^2+(75-82.3)^2+(69-82.3)^2]/10

问：计算这次考试成绩的方差

问：？

问：

答：=(18.49+32.49+59.29+7.29+2.89+32.49+13.69+5.29+53.29+176.89)/10=402.1/10=40.21

答：答，方差是40.21

答：正确答案是平均值m=(78+88+90+85+84+88+86+80+75+69)/10=823/10=82.3方差=[(78-82.3)^2+(88-82.3)^2+(90-82.3)^2+(85-82.3)^2+(84-82.3)^2+(88-82.3)^2+(86-82.3)^2+(80-82.3)^2+(75-82.3)^2+(69-82.3)^2]/10=(18.49+32.49+59.29+7.29+2.89+32.49+13.69+5.29+53.29+176.89)/10=402.1/10=40.21答，方差是40.21

答：明白了吗？亲

答：正确答案是平均值m=(78+88+90+85+84+88+86+80+75+69)/10=823/10=82.3x1=78,x2=88,x3=90,x4=85,x5=84,x6=88,x7=86,x8=80,x9=75,x10=69根据方差计算公式s^2=[(x1-m)^2+(x2-m)^2+(x3-m)^2+...+(x10-m)^2]/10=[(78-82.3)^2+(88-82.3)^2+(90-82.3)^2+(85-82.3)^2+(84-82.3)^2+(88-82.3)^2+(86-82.3)^2+(80-82.3)^2+(75-82.3)^2+(69-82.3)^2]/10=(18.49+32.49+59.29+7.29+2.89+32.49+13.69+5.29+53.29+176.89)/10=402.1/10=40.21答，方差是40.21

答：最后一段是比较详细的计算过程