c
\(\,{\alpha _{nk}} = \,\,\,\,\frac{\lambda }{d}\,\,\,\, \Rightarrow \,\,\,{\alpha _{nk}} = \,\,\,0.{2^ \circ }\,\,\, \Rightarrow \,\,\alpha \,\, \propto \,\,\,\lambda \)

\(\frac{{{\alpha _{_w}}}}{{{\alpha _{nk}}}}\,\,\, = \,\,\,\frac{{{\lambda _w}}}{{{\lambda _{_{nk}}}}}\,\, = \,\,\,{\lambda _w} = \,\,\,\frac{{{\lambda _{_{nk}}}}}{\mu }\,\,\,\)

\({\alpha _w} = \,\,\,\frac{{{\alpha _{_{nk}}}\lambda }}{{\mu \lambda }}\,\,\, = \,\,\,\,\frac{{0.2\,\, \times \,\,3}}{4}\,\,\, = \,\,\,0.15\)