Answer:
5.5
Step-by-step explanation:
ZX is the radius of circle X but it is also de diamenter of circle Y because it goes from one side to the other of the circle and passes through the center.
Then, if ZX is the diameter of circle Y, half the diameter is the radius, so the radius of circle Y will be:
Radius = ZX/2
Radius = 11/2
Radius = 5.5
Therefore, the answer is 5.5