certain list of 100 data...PT

AjayM520 · Posted: Mon Aug 18, 2008 1:26 pm Post subject: certain list of 100 data...PT

needs some quick help....thanks

dbart06 · Posted: Mon Aug 18, 2008 1:42 pm Post subject:

ans is 6 & 6. Why?

if you add 6 & 6 to the list the, avg does not change and adding the two #'s will actually make the std dev smaller because you have more #'s that are less from the mean(std dev).

gmattester · Posted: Tue Aug 19, 2008 9:23 pm Post subject: Need help with this problem

Can someone explain this plz.

Vignesh.4384 · Posted: Tue Aug 19, 2008 9:58 pm Post subject:

gmattester,

Take an eg of the set {2 4 6}
The mean will be 4.
The standard deviation can be found as [ (-2)^2 + 0^2 + (2)^2 /3 ]^1/2 (hope u get this step)

standard deviation = ( 8/3 ) ^ 1/2

When u add 4 and 4 to the set mentioned above ..

The standard deviation can be found as [ (-2)^2 + 0^2 + 0^2 + 0^2+ (2)^2 /5 ]^1/2

If u notice the denominator increases but numerator does not when 4 and 4 are added to {2 4 6}

gmattester · Posted: Wed Aug 20, 2008 7:15 am Post subject:

Thanks Vignesh .......
Nice explanation.It's clear now