Answer
$T_A=8T_B$
Work Step by Step
As we know that the time period for satellite A is
$T_A=2\pi\sqrt{\frac{R_A^3}{GM}}$
Similarly for satellite B
$T_B=2\pi\sqrt{\frac{R_B^3}{GM}}$
Now we can find the ratio of the two satellites time period as:
$\frac{T_A}{T_B}=\sqrt{\frac{R_A^3}{R_B^3}}$
Substituting $R_A=4R_B$, we obtain:
$T_A=8T_B$
