Fun, geometry disguised as probability.
That's a pentagon, which we can view as 10 right triangles with legs a and s/2 (half of s) and hypotenuse r. So area of the pentagon is
P = 10 × (1/2) a (s/2) = 10 (1/2) (3.2) (4.7/2) = 37.6
The area of the circle is πr² so the circle area is
C = π (4²) = 50.265482
The white area is the difference, C-P, and the probability we seek is the fraction of the circle that's white, so (C-P)/C.
p = (C-P)/C =1-P/C = 1-37.6/50.265482 = 0.251971
Answer: 0.25
Higher than I would have guessed from the figure.
