Two good train each 750 m long, are running in opposite directions on parallel tracks. Their speeds are 45 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 most appropriate option
A) 12 sec B) 24 sec C) 48 sec D) 72 sec E) None
Sol.   Relative Speed = (45 + 30) km / hr   = (75 x 5 / 18) m/sec   = (125/6) m/sec.   Distance covered = (750 + 750)= 
<gadget id="calculator">(750 + 750)</gadget>
<output>1_500</output>
1500m.   Required time= (1500 x 6 / 125) sec = 72 sec.   Answer 72 sec
<result>D</result>
Two good train each 750 m long, are running in opposite directions on parallel tracks. Their speeds are 45 km / hr and 30 km /hr respectively. Find the time taken by the slower train to pass the driver of the faster one.