Question

已知样本x,y,99,100,101的平均数为100,方差为2,球x,y的值.

Answer 1

x+y+99+100+101=100*5

-> x+y=200 y=200-x

(x-100)^2+(y-100)^2+1+0+1=2*5

-> (x-100)^2+(100-x)^2=8

|x-100|^2=4

|x-100|=2

x=102,y=98 or x=98,y=102