Power of String Oscillation

Relevant wiki: Power of a Wave

The energy carried in a wavelength for a wave of wavelength (\lambda), mass density $\mu$ , angular frequency $\omega$ , and amplitude $A$ is:

$E = \frac12 \mu \lambda \omega^2 A^2.$

Solving for $\lambda$ and replacing $\omega = 2\pi f$ the angular frequency for the given linear frequency, one has:

$\lambda = \frac{2E}{\mu (2\pi f)^2 A^2}.$

Substituting in all given values, one finds $0.3 \text{ m}$ to be the wavelength corresponding to the given values.