A train cover a distance of 3584 km in 2 days 8 hours. If it covers 1440 km on first day and 1608 km on second day, by how much does average speed of train for remaining part of journey differ from that for entire journey?

$$\eqalign{ & {\text{Given , }} \cr & {\text{Train cover 3584 kms in 2 days 8 hours}} \cr & \left( {2\,{\text{days 8 hours = }}\frac{7}{3}{\text{ days}}} \right) \cr & {\text{Average speed = }} {\frac{{3584}}{{ {\frac{{7}}{{3}}}}}} \cr & {\text{ = 1536 km/day = }}\frac{{1536}}{{24}}{\text{ = 64 km/h}} \cr & {\text{Distance covered in two days}} \cr & {\text{ = 1440 + 1608 = 3048 km}} \cr & {\text{Remaining distance for third day}} \cr & {\text{ = 3584 }} - {\text{3048 = 536 km}} \cr & {\text{Third day 536 km is covered in }} \cr & {\text{8 hour with speed of}} \cr & {\text{ = }}\frac{{536}}{8} = 67{\text{ km/h }} \cr & {\text{( 3rd day total 536 km distance}} \cr & {\text{ covered by 67 km/hr in 8 hr)}} \cr & \therefore {\text{Difference of average speedm}} \cr & {\text{ = 67}} - {\text{64 = 3 km/hr}} \cr} $$