A thief seeing a policeman from a distance of 400 m started running at a speed of 16 km/h. The policeman chased him immediately with a speed of 18 km/h and the thief was caught. What is the distance run by the thief before he was caught by the policeman?

Distance between thief and policeman = 400 m

Speed of the thief = 16 km/h

Speed of the policeman = 18 km/h

Relative speed (when moving in the same direction):

Relative speed=Speed of policeman−Speed of thief

Time taken to catch the thief:

​$$\text{Time} = \frac{\text{Distance between them}}{\text{Relative speed}}$$​​

Distance run by the thief:

Distance= Speed of thief × Time