A thief was spotted by a policeman from a distance of 660 meters.  When the policeman started the chase, the thief also started running.  If the speed of the thief was 9 km/h and that of the policeman was 12 km/h, then how far would the thief have run before the policeman caught up with him?

1980 meter

⇒ Relative speed = 12 - 9 = 3 km/h or 3 × \(\frac{5}{18}\) m/sec = \(\frac{5}{6}\) m/sec

⇒ Time to catch = \(\frac{Distance}{Time}\) = \(\frac{660}{\frac{5}{6}}\) = 792 seconds

Hence,

⇒ Distance covered by the thief in 792 seconds = 9 × \(\frac{5}{18}\) × 792 = 1980 meter