frequency of a simple harmonic motion

Question

Fig shows a mass attached to two springs. The mass moves along a horizontal tube with one spring stretched and the other compressed. A narrow marked on the mass indicates its position on a scale. Fig1 shows the situation when mass is displaced through a distance x from its equilibrium position. The mass is experiencing an acceleration a in the direction shown. Fig2 shows a graph of the magnitude of the acceleration against the displacement x.

Use data from figure to show that there frequency of the simple harmonic oscillations of the mass is about 5Hz

fig-1

fig-2

Summary : frequency of a simple harmonic motion