Total area of the rectangle = 12 × 24 = 288
The non-shaded regions make up a semicircle with radius 12, so the non-shaded region has area = 1/2 × π × 12² = 72π
The area of the shaded region is then 288 - 72π.
The probability of picking a point in the shaded region is then
(288 - 72π) / 288 ≈ 0.215
