Simple Harmonic Motion

As shown in the figure, a block of weight 20 N is connected to the top of a smooth inclined plane by massless spring of constant $8 \pi^2 \mathrm{Nm}^{-1}$. If the block is pulled slightly from its mean position and released, the period of oscillations is

(Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )