A policeman spots a thief at a distance of 200 m and starts chasing him. While the policeman runs at a speed of 9 km/ h, the thief runs at a speed of 7 km/ h. After how long will the policeman catch the thief?

As per the questions, the thief is 200 m ahead of the policeman when the policeman started running for catching him. The speed of policeman is 2 km/h (9-7=2) more than the thief.

So 1000 m = 1 km

1 m = 0.001 km

200 m = 0.2 km

time taken by the policeman to catch the thief = $$\frac{disatnce\ between\ policeman\ and\ thief\ initially}{effcetive\ speed}$$ = $$\frac{0.2}{2}$$

= 0.1 hour

1 hour = 60 minutes

So 0.1 hour = 6 minutes