A spherical chocolate ball has a layer of ice-cream of uniform thickness around it. When the thickness of the ice-cream layer is 1 cm, the ice-cream melts at the rate of $81 \mathrm {~cm} ^ { 3 } / \mathrm { min }$ and the thickness of the ice-cream layer decreases at the rate of $\frac { 1 } { 4 \pi } \mathrm {~cm} / \mathrm { min }$. The surface area (in $\mathrm { cm } ^ { 2 }$) of the chocolate ball (without the ice-cream layer) is : (1) $196 \pi$ (2) $256 \pi$ (3) $225 \pi$ (4) $128 \pi$
A spherical chocolate ball has a layer of ice-cream of uniform thickness around it. When the thickness of the ice-cream layer is 1 cm, the ice-cream melts at the rate of $81 \mathrm {~cm} ^ { 3 } / \mathrm { min }$ and the thickness of the ice-cream layer decreases at the rate of $\frac { 1 } { 4 \pi } \mathrm {~cm} / \mathrm { min }$. The surface area (in $\mathrm { cm } ^ { 2 }$) of the chocolate ball (without the ice-cream layer) is :\\
(1) $196 \pi$\\
(2) $256 \pi$\\
(3) $225 \pi$\\
(4) $128 \pi$