hello, is this correct?

A= pi * r^2 

Circumferance= 2 * pie * r 

d = 2r 

if we have got the information about the circle is this right? 

 what is the likelihood of hitting a point inside circle C which is inside cirlce K ? 

is the area of circle C divided by the area of circle K

what is the likelihood of hitting a point inside the donut circle B which is inside K

Area of  B - Area of C / Area of Circle K

hitting a point inside A 

p(A) =  1- (p(C) + p(B)) 

or

100% - ( (p(C) + p(B))

or 

Area of K - Area of B / Area k