Question

If a man walks at a speed of 4 kmph, how long will it take him to walk 3 km?

Answer 1

1 km = 1000 m

4 km in 1 hour, 4 km in 60 minutes 

That is

    2 km in 30 minutes
+ 1 km in 15 minutes
   3 km in 45 minutes.

Answer 2

   15
4)`overline 60`
- 4         That is 1 km in 15 minutes
  20       Hence, 3 km in 15 x 3 = 45 min
-20   
  00   

∴ 3 km in 15 x 3 = 45 min.