A policeman chases a thief. The speed of the policeman and thief are 18 km/h and 6 km/h, respectively. If the policeman started 10 minutes late, at what distance will he catch the thief?

Speed of the thief = 6km/h
Speed of the policeman = 18km/h

The policeman starts 10minutes late. In these 10minutes, the distance covered by the thief is:

Distance=Speed×Time=6×
60
10
​
=1km
Relative speed of the policeman with respect to the thief:

v
rel
​
=18−6=12km/h
Time taken by the policeman to catch the thief:

Time=
Relative Speed
Initial Distance
​
=
12
1
​
hours
Distance covered by the policeman in this time (the point where he catches the thief):

Distance=Speed of Policeman×Time=18×
12
1
​
=1.5km