Keeping the banking angle same, to increase the maximum speed with which a vehicle can travel on a curved road by 10 percent the radius of curvature of the road has to be changed from 20 m to :

Question

$$\begin {array} {1 1} (a)\;6\;m & \quad  (b)\;18\;m \\  (c)\;24.2\;m & \quad (d)\;30.5\;m \end {array}$$