The correct unit for the speed of light is  [ m s⁻¹ ].
Time = (distance) / (speed)
Time = (9.3 x 10^7 miles) x (1609 m/mile) / (3 x 10^8 m/s) = 498.8 seconds .
That would be  <em>8.31 minutes</em>.   
        
             
        
        
        
To solve the exercise it is necessary to take into account the concepts of wavelength as a function of speed.
From the definition we know that the wavelength is described under the equation,

Where,
c = Speed of light (vacuum)
f = frequency
Our values are,


Replacing we have,



<em>Therefore the wavelength of this wave is  </em>
</em>