Flight time is
[tex]T= \frac{2V}{g} sin \phi [/tex]
In the time interval [tex][ \frac{ \pi }{6} , \frac{ \pi }{4} ][/tex], the average tme is
[tex] T_{avg} = \frac{1}{ \frac{ \pi }{4}- \frac{ \pi }{6} } \int\limits^ \frac{ \pi }{6} _ \frac{ \pi }{4} {sin \phi } \, d \phi [/tex]
[tex]=- \frac{24V}{g \pi } [cos \phi ] _{ \pi /6} ^{ \pi /4} [/tex]
[tex]= \frac{24V}{ \pi g} (0.1589)[/tex]
[tex]=1.214( \frac{V}{g} )[/tex]
Answer: [tex] T_{avg} =1.214( \frac{V}{g} )[/tex]
