\(^w{\mu _g} = \,\,\,\frac{{^a{\mu _g}}}{{^a{\mu _w}}}\,\, = \,\,\,\frac{{1.53}}{{1.33}}\,\,\, = \,\,1.15\)

\(\,\,\,\because \,{\,^w}{\mu _g} = \,\,\,\frac{{\sin \frac{{A + {\delta _m}}}{2}}}{{\sin \frac{A}{2}}}\,\,\)

\( \Rightarrow \,\,\,\frac{{\sin \,\,(A + {\delta _m})}}{2}\,\, = \,{\,^w}{\mu _g}\,\, \times \,\,\sin \,\frac{A}{2}\,\, = \,\,1.15\,\,\sin \,\,\,\frac{{{{60}^ \circ }}}{2}\,\, = \,\,0.575\)

\(\frac{{A + {\delta _m}}}{2}\,\, = \,\,{\sin ^{ - 1}}\,\,(0.575)\,\, = \,\,{35.1^ \circ }\,\)

\(\therefore \,\,\,\,{\delta _m} = \,\,35.1\,\, \times \,\,2\,\, - \,\,60\,\, = \,\,{10.2^ \circ }\)