The average speed of a bus is one-third of the speed of a train. The train covers 1125 km in 15 hours. How much distance will the bus cover in 36 minutes ?

Speed of the train :
$$\eqalign{ & = \left( {\frac{{1125}}{{15}}} \right){\text{ km/hr}} \cr & = 75{\text{ km/hr}} \cr} $$
Speed of the bus :
$$\eqalign{ & = \left( {\frac{1}{3} \times 75} \right){\text{ km/hr}} \cr & = 25{\text{ km/hr}} \cr} $$
Distance covered by the bus in 60 min = 25 km
Distance covered by the bus in 36 min :
$$\eqalign{ & = \left( {\frac{{25}}{{60}} \times 36} \right){\text{ km}} \cr & = 15{\text{ km}} \cr} $$