请教各位XDJM

zida

I checked with EXCEL, definitely

D.

zida

I checked with EXCEL, definitely D.

[此贴子已经被作者于2003-12-21 7:09:27编辑过]

bose0008

standard deviation is the measure of the degree of dispersion.

if we put the original sample on a x-y coordinate system, the second sample is basically moving every single piece of data (also including the mean of the original sample) toward positive y direction by the same amount, it does not change the degree of dispersion! thus the new stdev. does not change.

if u do want to check equation, then the mean of the new sample is increased by the same amount as every other number in the sample. (Xn-mean)^2 for each item doesn't change. number of sample doesn't change, thus stdev. does not change.

feckham23

感恩啊..想了好久