= Solution
Convert the skin <temperature> to $T_s=308.15\,\mathrm K$. To locate the peak per unit <wavelength> in <Planck's law>, write $x=hc/(\lambda k_BT)$ and maximize $x^5/(e^x-1)$. Its positive stationary point obeys
$$
5(1-e^{-x})=x,\qquad x=4.965114\ldots.
$$
This gives <Wien's displacement law>, $\lambda_{\max}T=2.89777\times10^{-3}\,\mathrm{m\,K}$. Hence
$$
\boxed{\lambda_{\max}=9.40\times10^{-6}\,\mathrm m\simeq9.4\,\mathrm{\mu m},}
$$
in the thermal <infrared>. A peak per unit <frequency> would occur at a different spectral position; this answer uses the conventional wavelength peak.
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