Two vehicles each 900 m long are running in opposite directions on parallel paths. Their speeds are 50 km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one?
Choose the correct choice.
A) 77 sec
B) 66 sec
C) 48 sec
D) 81 sec
E) 45 sec
Relative speed = 50 + 30= 
<gadget id="calculator">50 + 30</gadget>
<output>80</output>
80 km/hr.   80 * 5/18= 200/9 m/sec.   Distance covered = 900 + 900 = 180 m.   Required time = 1800 * 9/200= 
<gadget id="calculator">1800 * 9/200</gadget>
<output>81</output>
81 sec.   Answer: 81 sec
<result>D</result>
Two vehicles each 900 m long are running in opposite directions on parallel paths. Their speeds are 50 km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one?