P(8 or 12) = 1/6
P(not 8 or 12 = 5/6
Let the expected points fro one roll be X.

The answer is -(1/6) points.
Answer:
5 parts are shaded and 4 parts are white so:
There are 9 parts all together.
We can then form ratio's of the white areas and the shaded areas:
White Area Ratio =

Shaded Area Ratio =

Let the area of sqaure be equated to x, which means let the entire area of the square equal to x:
x = Area of whole square
Now we can form an equation :

So now we just need to solve for x:


The area of the square is:

Each exterior angle of a regular 25-gon = 360/25 = 14.4 deg. and each interior angle= 165.6 deg.