An aeroplane covers a certain distance at a speed of 400 km/hr in 8 hours. To cover the same distance in 5 hours, the speed of the areoplane will be:

640 km/hr

Speed of the aeroplane = $\frac{distance}{time}$

⇒                  400         = $\frac{distance}{8}$ 

⇒                  distance   = 400 x 8 = 3200 km

Speed of the aeroplane when it covers the same distance in 5 hours = $\frac{3200}{5}$  

                                   = 640km/hr