To know the probability we need to know the area of the yellow zone and the area of the rest. So, the yellow circle (that contains white, red and blue circle) has a radius of 1+2+2+2=7. Then the area is
Area yellow=
But, the yellow zone is yellow circle - blue circle.
Area blue =
Then, the yellow zone will be
Area target= 14*14 = 196.
So, the probability is the yellow zone divided by the target (total area):