A thief runs away from A with a speed of 20 km/hr. A police from a station 60 km away started chasing him after 1 hr. with a speed of 40 km/hr. Time taken by the police to catch the thief is :  Choose the correct choice from the following choices:  A) 4 hrs  B) 4.5 hrs  C) 5.4 hrs  D) 6 hrs.  E) None of these
Explanation :   Solution: Distance traveled by the thief in 1 hr. = 20 km.   Total distance of them after 1 hr = (60 + 20)= 
<gadget id="calculator">(60 + 20)</gadget>
<output>80</output>
80 km.   Their relative speed= (40 - 20)= 
<gadget id="calculator">(40 - 20)</gadget>
<output>20</output>
20 km/hr.   Time taken to catch the thief= 80/20= 
<gadget id="calculator">80/20</gadget>
<output>4</output>
4 hrs.   4 hrsnswer : 4 hrs
<result>A</result>
A thief runs away from A with a speed of 20 km/hr. A police from a station 60 km away started chasing him after 1 hr. with a speed of 40 km/hr. Time taken by the police to catch the thief is :