View Full Version : Normal distribution
jbk2000
May 2, 2010, 02:41 AM
On the same diagram sketch three normal distributions, one with mean 0 and standard deviation 2, one with mean 0 and standard deviation 4, and one with mean 3 and standard deviation 2. Make sure that you label each of the three graphs.
I do not understand how I am supposed to do this, can someone please help me.
Unknown008
May 2, 2010, 03:08 AM
Have you ever seen a normal distribution curve?
This one is a good one:
http://www.comfsm.fm/~dleeling/statistics/normal_curve.gif
The line at the bottom gives the values where \mu is the symbol for the mean.
The blue areas denote the first standard deviations (denoted by \sigma, both positive (the right one, \mu + \sigma) and negative (the left one \mu - \sigma).
The red areas denoted the second standard deviations and the orange the third standard deviations, where the curve is very close to the horizontal line.
a) If the mean is 0, then replace \mu by 0.
From the mean towards the right, \mu + \sigma will be 0 + 2 = 2, \mu + 2\sigma will be 0 + 4 = 4 and \mu + 3\sigma will be 0 + 6 = 6.
From the mean towards the left, \mu - \sigma will be 0 - 2 = -2 and so on.
Is that clear enough?
Remember that the curve should be symmetric about the mean, the curve is very near to the horizontal line at 3 standard deviations.
Lochinvar West
May 2, 2010, 03:33 AM
This site may help:
An Introduction to Excel's Normal Distribution Functions (http://www.exceluser.com/explore/statsnormal.htm)
singh2010
May 2, 2010, 04:53 AM
Seems easy enough to do. Thanks for the help once again!