Geometric Probablity

This is not a well written question.

Assuming there is an equal chance of point d being the same point as any point in plane p, then the chance of it landing in region a 'r' would be area_of_r / area_of_p.

(If this is the assumption, it should be stated in the poblem.)

However the area of a plane is infinite -- and 16/infinity is undefined.

I am afraid this problem doesn't have an answer.

O yes I was meaning the plane's area was infinite so i guess it has no answer.

Your chances are about zero, because the plane is infinite and R is not, Probability = Area of r / Area of p, or 16 / infinity. So unless r is special - like the origin, and d is also special like biased to be close to the origin you chances are diminishingly small.