A body revolves around the sun 27 times faster than that of the earth. The ratio of their radii is

Let the time period of earth = T

${\text{T}}_{\text{E}}=\text{T}$

The planet is revolving 27 times faster

${\text{T}}_{\text{B}}=\frac{\text{T}}{27}$     

We have    

$\frac{{\text{T}}_{\text{A}}^{\text{2}}}{{\text{T}}_{\text{B}}^{\text{2}}}=\frac{{\text{R}}_{\text{A}}^{\text{3}}}{{\text{R}}_{\text{B}}^{\text{3}}}$   

then$\frac{{\text{R}}_{\text{A}}}{{\text{R}}_{\text{B}}}=\frac{1}{9}$