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learn math?
Then using these great
math
lesson plans made for teachers can provide your children extra help. The
lesson plans will help you follow along with their
math
curriculum.
You can find great literature on
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Mathematics : Statistics Applet
The statistics applet below calculates the sample mean, the sample standard deviation, and constructs a 95% confidence interval for data values entered in.
Click Here to Launch the Statistics Applet
(This will launch in a new browser Window, or click here to load as a page)
The Mathematics Behind It
The sample mean is calculated by summing up all of the entered data, and then dividing by the number of data points.
The sample standard deviation is calculated by the following
forumla:
The formula in words says take the summation from 1 to n of the quantity x(i) minus x-bar quantity squared, and divide by (n-1).
Where n is the number of data points, x(i) is the individual data points, and x-bar is the sample mean.
Note the above forumla is the standard deviation squared, or the variance, take the positive square root for the standard deviation.
The confidence interval is calculated by x-bar, the sample mean, +/- the t-value, which is retrieved from a table, for 95% its 2.776 with 4 degrees of freedom.
I just released that I have made a mistake. The t-value changes depending
on how many data points you have, I forgot to account for that. (whoops! - I'll fix it
later).
So take x-bar +/- the t-value times the standard deviation over the square root of n.