sd2

any takers on this ?

Mean for x, y, z = m
Mean for x+5, y+5, z+5 = [(x+y+z)+15]/3 = m+5
Because the difference between m+5 and either x+5, y+5 or z+5 is the same as the difference between m and x, y or z (eg. m+5-x-5 = m-x), you will have the same standard deviation.

SD should be "d" only.
Remember this two rules..

SD(x+c) = SD(x) c--> constant.
SD(x * c) = c*SD(x)

gr8 explanation dana

amitabhprasad wrote:SD should be "d" only.
Remember this two rules..

SD(x+c) = SD(x) c--> constant.
SD(x * c) = c*SD(x)

Thanks for reminding.. i forgot the multiplication rule..

Once again SD questions test your knowledge not your calculation skills.

Standard Deviation is the distance from the average

A B C can be 0 0 and 0 and the average is 0 and the SD is 0 because they are all the same numbers

if you add the same number to all of them

5 5 5 well, this time the average will INCREASE with the SAME number you added to each number

So NUMBER - AVERAGE = WILL BE THE SAME

and as a result SD wont change!