The ratio of the speed of a bus to that of a train is 15 : 27. Also, a car covers a distance of 720 km in 9 hours. The speed of the bus is three-fourths of the speed of the car. How much distance (in km) will the train cover in 7 hours?

A car covers a distance of 720 km in 9 hours.

Speed of car = $$\frac{distance\ covered}{time}$$

= $$\frac{720}{9}$$

= 80 km/h

The speed of the bus is three-fourths of the speed of the car.

speed of the bus = $$\frac{3}{4}\times80$$

= $$3\times20$$

The ratio of the speed of a bus to that of a train is 15 : 27.

speed of the train = $$\frac{60}{15}\times27$$

= $$4\times27$$

= 108 km/h

Distance covered by the train in 7 hours = $$speed\times time$$

= $$108\times 7$$

= 756 km