Z score

[Amjad]

I am having difficulty understanding the Z score. Its looks like that SD and Z score is doing the same function? Could you please explain with small example?

Thanks,
A.

[JohnM]

The z score tells you how many standard deviations away from the mean a particular value is.

For examle, if you have a data set with mean = 20 and std dev = 4, then 24 would be:

z = (x-mu)/s
z = (24-20)/4 = 1.0 standard deviation above the mean

[Amjad]

thank you John, You are really great in answering so quikly.
A.