First u need to find the area of whole which is made of two circles
Area of a small circle=πr1^2=π*36=113.04
Area of a Big circle A1 =πr2^2 =π*144 =452.16
Now the whole area A2 =A1+A1= 565.2
Now the area of a shaded region=A2-A1= 339.14
Probability of hitting the shaded area=339.14/565.2=0.6
So 0.6 is the probability.