A clock which keeps correct times at $20^{\circ}C$, is subjected to $40^{\circ}$. If coefficient of linear expansion of the pendulum is $12 \times 10^{-6}/^{\circ}$ C. How much will it gain or lose time ?

Question

$$\begin {array} {1 1} (a)\;10.3\;s/day & \quad (b)\;20.6\;s/day \\ (c)\;5\;s/day & \quad (d)\;20\;min/day \end {array}$$