Two goods trains each 75 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?	Pick.
A) 2.3 sec B) 4.2 sec C) 48 sec D) 7.2 sec E) 9 sec
Relative speed = 45 + 30= 
<gadget id="calculator">45 + 30</gadget>
<output>75</output>
75 km/hr.   75 * 5/18= 125/6 m/sec.   Distance covered = 75 + 75= 
<gadget id="calculator">75 + 75</gadget>
<output>150</output>
150 m.   Required time= 150 * 6/125= 
<gadget id="calculator">150 * 6/125</gadget>
<output>36/5 = around 7.2</output>
7.2 sec.   Answer:7.2 sec
<result>D</result>
Two goods trains each 75 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?