A thief steals a car at 1.30 pm and drive it off 40 km/hr. The ft is discovered at 2 pm and owner sets off in anor car at 50 km/hr he will catch thief at :

Distance covered by thief in (2 pm - 1.30 pm)
= $$\frac{1}{2}$$ hr at speed of 40 km/hr
= 40 × $$\frac{1}{2}$$
= 20 kms
Their relative speed in same direction :
= (50 - 40) km/hr
= 10 km/hr
According to the question,
20 km, is the distance that has to be covered by owner to catch the thief.
$$\eqalign{ & {\text{Required time}} = \frac{{20{\text{ km}}}}{{10{\text{ km/hr}}}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 2{\text{ hours}} \cr} $$
Therefore, he will over take the thief at :
= 2 pm + 2 hr
= 4 pm