A thief escapes custody at 10 a.m. He runs at a speed of 40 km/h. The policeman starts chasing the thief at 11:30 a.m., starting from the point from where the thief escaped custody. The speed of the policeman is 60 km/h. At what time will he catch the thief?

Speed of thief = 40 km/h

Speed of the policeman = 60 km/h
A thief escapes custody at 10 a.m. But the policeman starts chasing the thief at 11:30 a.m.

So the distance traveled by the thief till 11:30 a.m = $$40\times1.5$$ [11:30 a.m. - 10 a.m. = 1.5 hour]

= 60 km

Time taken by policeman to catch thief = $$\frac{relative\ dis\tan ce}{relative\ speed}$$

= $$\frac{60}{60-40}$$

= $$\frac{60}{20}$$

= 3 hours

As we know that policemen started at 11:30 a.m. So 11:30 a.m. + 3 hours = 2:30 p.m.

So at 2:30 p.m., the policeman will catch the thief.