Explanation:
\(P E=\dfrac{1}{2} m \omega^{2} x^{2} ; K E=\dfrac{1}{2} m \omega^{2}\left(A^{2}-x^{2}\right)\)
At \(x = \frac{A}{2};PE = \frac{1}{2}m{\omega ^2}\left( {\frac{{{A^2}}}{4}} \right) = \frac{1}{8}m{\omega ^2}{A^2}\,\,\,\,\,\,\,\left( 1 \right)\)
\(KE = \frac{1}{2}m{\omega ^2}\left( {{A^2} - \frac{{{A^2}}}{4}} \right) = \frac{3}{8}m{\omega ^2}{A^2}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\left( 2 \right)\)
From equation (1) and (2), we get
\(\dfrac{P \cdot E}{K E}=\dfrac{\dfrac{1}{8} m \omega^{2} A^{2}}{\dfrac{3}{8} m \omega^{2} A^{2}}=\dfrac{1}{3} ; \dfrac{P \cdot E}{K E}=\dfrac{1}{3}=1: 3\)