On an overcast day the directional distribution of the solar radiation incident on the earth's surface may be approximated by an expression of the form \(I_{i}=I_{n} \cos \theta\), where \(I_{n}\) is the total intensity of radiation directed normal to the surface and \(\theta\) is the zenith angle. What is the value of \(I_{n}\) when the incident solar irradiation is \(G=200 \mathrm{~W} / \mathrm{m}^{2}\) ?