A man rides at the speed of 18 km/hr, but stops for 5 min to change horse at the end of every 7 km. Find the time taken by him to cover the distance of 90 km.

06 hrs

Speed = 18km/hr

Distance = 90km

Minimum time without stoppage = \(\frac{90}{18}\) = 5hrs.

If he stops for 5 mins. after every 7 km , then to cover 90km , he will stop for at least 12 times.

So, total stoppage time = 12 × 5 = 60 min i.e. 1 hour

Total time taken to cover 90 km = 5 + 1 = 6hrs.