For finding the probability that a certain point is chosen in an area, there are many formulas you can use depending on the shapes. For most equations, you will need to define a boundary for the probability.
Then choose the area that you want to assess as favorable (must be less than the total area)
You can then take the area of both the favorable and the total area.
Probability can be found with fav. area/ total area.
To change to a percent value, multiply by 100!
Hope this helps. I use this to calculate the odds of my boss saying im a screwup and the odds that he doesnt. Lets just say that the shades "favorable" area is very close to the total area :(
