Standard Normal Distribution: If a set of observations is di

[abc4616]

If a set of observations is distributed as N(u, std. dev.^2), what is the percentage of the observations will differ from the mean by:

a) less than 1 standard deviation?
b) less than 2 standard deviation?
C) less than 3 standard deviation?

How can I prove this?

 

[royhaas]

Use a standard normal table.

 

[tkhunny]

Isn't this the number 1, most basic property of the Normal Distribution? There absolutely must be a drawing in your book with these values filled in.