It is given that,
wavelength, [tex]\lambda=897\ Km[/tex]
distance covered, [tex]d=3280\ Km[/tex]
time, [tex]t=4.18\ h[/tex]
(a) Speed is, [tex]s=\dfrac{d}{t}[/tex]
[tex]s=\dfrac{3280\ Km}{4.18\ h}[/tex]
[tex]s=784.6\ Km/h[/tex]
[tex]s=784.6\times \dfrac{5}{18}\ m/s[/tex]
[tex]s=218\ m/s[/tex]
(b) Frequency is, [tex]\nu=\dfrac{v}{\lambda}[/tex]
So, [tex]\nu=\dfrac{784.6\ Km/h}{897km}[/tex]
[tex]\nu=0.874\ Hz[/tex]
(c) Time period, [tex]T=\dfrac{1}{\nu}[/tex]
[tex]T=1.144\ h[/tex]
Hence, this is the required solution.