A bus normally takes 4 hours to cover a route at 45 km/h. At what speed must it run to cover the route in 3 hours 36 minutes?

Explanation

1. 01

   Route length $= 45 \times 4 = 180$ km.

2. 02

   3 h 36 min $= 3 + \frac{36}{60} = 3.6$ h.

3. 03

   Required speed $= \frac{180}{3.6} = 50$ km/h.