Two goods trains each 500 m long are running in opposite directions on parallel tracks. Their speeds are 20 km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one? Options.
A) 22 B) 88 C) 48 D) 99 E) 72
Relative speed = 20 + 30= 
<gadget id="calculator">20 + 30</gadget>
<output>50</output>
50 km/hr.   50 * 5/18= 125/9 m/sec.   Distance covered = 500 + 500= 
<gadget id="calculator">500 + 500</gadget>
<output>1_000</output>
1000 m.   Required time= 1000 * 9 /125= 
<gadget id="calculator">1000 * 9 /125</gadget>
<output>72</output>
72 sec   Answer: 72
<result>E</result>
Two goods trains each 500 m long are running in opposite directions on parallel tracks. Their speeds are 20 km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one?