When a spring oscillator vibrates harmonically, when its displacement from the equilibrium position is 1 / 4 of the amplitude, what is its kinetic energy? 15/16

When a spring oscillator vibrates harmonically, when its displacement from the equilibrium position is 1 / 4 of the amplitude, what is its kinetic energy? 15/16

Total energy of spring oscillator:
At the maximum amplitude x, there is only elastic potential energy: 1 / 2kx ^ 2
Elastic potential energy at x / 4: 1 / 2K (x / 4) ^ 2
Kinetic energy = 1 / 2kx ^ 2-1 / 2K (x / 4) ^ 2 = 15 / 16 (1 / 2kx ^ 2)
15/16