set formulas

let A,B,C be arbitrary subsets of the finite set X. Illustrate this formula with an example or explain with a digram...how could i use a diagram to show this..some sort of venn?

|A U B U C|=|A| +|B| + |C|-|A and B| -|A and C| - |B and C| + |A and B and C|

thanks.

This is the addition rule for 3 events.

Here is an example and a diagram:

P(A)=.20, P(B)=.50, P(C)=.30, P(A and B)=.15, P(A and C)=.13

P(B and C)=.20, P(A and B and C)=.10

You can use the formula to get .62

From the diagram you can see the respective events.

Here is a pdf file to show you how its works.
Use the 'arrow keys' to page thru the document.
Note that the "+'s" indicate how often a region is counted.