Explanation

(b) Kinetic energy $K = \frac{1}{2}m\omega^{2}A^{2} - y^{2}$
At mean position $y = 0$
$K = \frac{1}{2}m\omega^{2}(A^{2})$
Potential energy $U = \frac{1}{2}m\omega^{2}y^{2}$ …(i)
$U\ at\ y = \frac{A}{2}$
$U = \frac{1}{2}\ \frac{mA^{2}}{4}\ \omega^{2}$ …(ii)
Dividing Eq. (i) by Eq. (ii), we get
$\frac{KE}{U} = \frac{4}{1}$