Let
$\begin{array}{c|c|c|c}
& \text{sphere }A & \text{sphere }B & \text{sphere }C \\ \hline
\text{Volume} & V_A & V_B & V_C \\ \hline
\text{Surface area} & S_A & S_B & S_C \\ \hline
\text{Radius} & R_A & R_B & R_C
\end{array}$
Note that all spheres are similar. Therefore, we have
$\begin{array}{rcl}
V_B : V_C & = & 1 : 8 \\
R_B : R_C & = & \sqrt[3]{1} : \sqrt[3]{8} \\
& = & 1 : 2
\end{array}$
and also
$\begin{array}{rcl}
S_A : S_B & = & 9 : 4 \\
R_A : R_B & = & \sqrt{9} : \sqrt{4} \\
& = & 3: 2
\end{array}$
Hence, we have
$\begin{array}{ccccccccccc}
R_A & : & R_B & & & = & 3 & : & 2 & & \\
& & R_B & : & R_C & = & & & 1 & : & 2 \\ \hline
R_A & : & R_B & : & R_C & = & 3 & : & 2\times 1 & : & 2 \times 2 \\
& & & & & = & 3 & : & 2 & : & 4
\end{array}$
Therefore, the radius of $A$ : the radius of $C=3:4$.
