A Carnot engine operating between two reservoirs has efficiency $\frac { 1 } { 3 }$. When the temperature of cold reservoir raised by $x$, its efficiency decreases to $\frac { 1 } { 6 }$. The value of $x$, if the temperature of hot reservoir is $99 ^ { \circ } C$, will be\\
(1) 16.5 K\\
(2) 33 K\\
(3) 66 K\\
(4) 62 K