[MOVED] Standard Deivation

Xtal

New member
Joined
May 21, 2013
Messages
6
Please don't bite my head off if this is in the wrong thread...

How do you get the range for 2 SD and 3 SD? I know the empirical rule. The mean is 80 and the standard deviation is 5.

I actually asked on yahoo answers and someone wrote:

If the mean is µ and the standard deviation is σ then the range for
1 SD is µ-σ to µ+σ,
2 SD is µ - 2σ to µ + 2σ
3 SD is µ - 3σ to µ + 3σ
and you know µ and σ.

What is the 2 and the 3 next to
σ?
 
Last edited:
Please don't bite my head off if this is in the wrong thread...

How do you get the range for 2 SD and 3 SD? I know the empirical rule. The mean is 80 and the standard deviation is 5.

I actually asked on yahoo answers and someone wrote:

If the mean is µ and the standard deviation is σ then the range for
1 SD is µ-σ to µ+σ,
2 SD is µ - 2σ to µ + 2σ
3 SD is µ - 3σ to µ + 3σ
and you know µ and σ.

What is the 2 and the 3 next to
σ?

2σ = 2 * σ

and similarly

3σ = 3 * σ

Where * means "multiplied by"
 
so, 2 x 5 and 3 x 5?
and that's how you get the range of SD?

so am i right in saying that the range for 1 SD is 75 - 85?

and 2 SD is 70 - 90?

that does not sound righttt
 
so, 2 x 5 and 3 x 5?
and that's how you get the range of SD?

so am i right in saying that the range for 1 SD is 75 - 85?

and 2 SD is 70 - 90?

that does not sound right Why Not?

.
 
i just thought the numbers would all be different. like 75 fits into 70 - 90... i thought they would be different, like for frequency distributions.

however, if that is correct, thank you.
 
Please don't bite my head off if this is in the wrong thread...
Okay, but in future, statistical questions might fit better in "Probability/Statistics" than in "Arithmetic". ;)
 
Top