Two lorries each 350 m long are running in opposite directions on parallel tracks. Their speeds are 40km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one?	Choose the most appropriate option:
A) 77 sec
B) 36 sec
C) 48 sec
D) 55 sec
E) 45 sec
Relative speed = 40 + 30= 
<gadget id="calculator">40 + 30</gadget>
<output>70</output>
70 km/hr.   70 * 5/18= 175/9 m/sec.   Distance covered = 350 + 350 = 200 m.   Required time = 700 * 9/175= 
<gadget id="calculator">700 * 9/175</gadget>
<output>36</output>
36 sec.   Answer: 36 sec
<result>B</result>
Two lorries each 350 m long are running in opposite directions on parallel tracks. Their speeds are 40km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one?