# Homework Help: Standerd and mean diviation

1. Jun 8, 2006

### minase

We just started slandered deviation in our precalcules class. We did not learn summation about sequence and series stuff. Our teacher just skipped all of that staff. I know that the standered deviation helps you to determine if the possible out comes are reasonable. How could you find the standered deviation and mean deviation? And how do you graph this I looked at the graph and it looks like a bell. In order to graph do you need to know the x and they values? I don't get what the teacher is talking about at all the formula with the sigma sign it doesn't make any sence to me. I don't have any resources that I could learn these things. Our teacher has all ready collected our books. IF you if you give me some sites that might be help full to me that would be really great.

2. Jun 8, 2006

### Ouabache

summation is an important concept to learn in order to hand-calculate the standard deviation and mean.

that's a vague definition. Here is a better one.

you find the standard deviation using a method. Here is a common description of that method.
If your graph looks like a bell, why are you asking how to graph it? If you mean how do you graph standard deviation, at each point they can be plotted along with the data values. By mean deviation, I take it you are talking about just the "mean", which is an important parameter in determining the standard deviation.

they certainly would be useful (what would you graph if you didn't know the x & y values? )

I would make an appointment to see your teacher during office hours and ask to go over that.
It is really easy to do that using a search engine.Here is one http://stattrek.com/Lesson2/Normal.aspx [Broken]. It is a tutorial outlining all the most common parameters used in a normal distribution (bell shaped curve)

Last edited by a moderator: May 2, 2017