Help with Standard Deviation

G_R

hey guys,

helping someone with a maths problem and after getting stuck any help appreciated.

topic is statistics and standard deviations

Question is:

The mean of the real numbers m and n is X.
The Standard Deviation is σ.

i) express σ in terms of m,n and X.
ii) Hence, show that σ = (m-n)/2


thanks lads

LeixlipRed

Ok, so you need to find X in terms of m and n first. Can you do that?

G_R

LeixlipRed wrote: »

Ok, so you need to find X in terms of m and n first. Can you do that?

ye we got that, and have subbed it into the SD formula, its just after that the problems arise

LeixlipRed

You just need to multiply it out. My latex is rusty so I can't show you. Just replace X with [latex]\frac{(n+m)}{2}[/latex]

G_R

LeixlipRed wrote: »

You just need to multiply it out. My latex is rusty so I can't show you. Just replace X with [latex]\frac{(n+m)}{2}[/latex]

its ok, thanks anyway LeixlipRed. I tried that and where you would expect them to cancel they dont. Thanks anyway, im probably justy multiplying out wrong

LeixlipRed

Just done it out there and it all works so you must have made a mistake.

G_R

LeixlipRed wrote: »

Just done it out there and it all works so you must have made a mistake.

ok thanks, ill try it again in the morning