Given the relationship T^2 = A^3, to compare the values of the orbital periods of X and Y, it would be easier to assign values. Since the Planet Y's distance A is twice that of Planet X's distance A, this can be shown below:
For Planet X (where A = 2):
T^2 = 2^3 T = 2.828
For Planet Y (where A = 4)
T^2 = 4^3 T = 8
Therefore, planet Y's orbital period is larger by (8/2.828) = 2.83 times.
