how do you find the geometric probability of a square in a square?
Without seeing the squares I can't say for sure.
But a good guess would be to do the following.
Calculate the areas of the inner square and of the outer square.
Divide the area of the inner square by the area of the outer square.
Say a square has sides 6" long, and inside it another square that has sides 4" long.
The area of the inner square is 16 sq in, and the area of the outer square is 36 sq in.
A missle hitting the large square has a 16 / 36 chance of landing in the small square.
You can reduce the fraction to its lowest terms, in this example, 4 / 9
or complete the division to get the percemtage. in this example, 44%
.