3,kx3+3.kxn+3,平均数为kx拔+3,标准差为/ks/\x0d（1）1/n(kx1+3,kx2+ 3,kx3+3.kxn+3)\x0d=1/n[(kx1+kx2+kx3...+kxn)+3n]\x0d=1/n[k(x1+x2+x3+...+xn)+3n]\x0d=k*(1/n)(x1+x2+x3+...+xn)+3=kx拔+3（2）标准差\x0d把kx1+3,kx2+ 3,kx3+3.kxn+3 减去（kx拔+3）得\x0dkx1-kx,kx2-kx,kx3-kx...kxn-kx即k(x1-x),k(x2-x)......k(xn-x)平方得k^2(x1-x)^2,k^2(x2-x)^2.k^2(xn-x)^2\x0d平均数即为方差为\x0d1/n[k^2(x1-x)^2+k^2(x2-x)^2+.+k^2(xn-x)^2]\x0d=k^2*(1/n)[(x1-x)^2+(x2-x)^2+.+(xn-x)^2]=k^2*s^2所以标准差为√K^2*s^2=ks