Two trains are moving in opposite directions at 60 km/hr and 90 km/hr. Their lengths are 2.10 km and 1.4 km respectively. The time taken by the slower train to cross the faster train in seconds is?
Answers:
A) 99
B) 277
C) 84
D) 96
E) 22
Relative speed = 60 + 90= 
<gadget id="calculator">60 + 90</gadget>
<output>150</output>
150 km/hr.= 150 * 5/18 = 125/3 m/sec.   Distance covered = 2.10 + 1.4= 
<gadget id="calculator">2.10 + 1.4</gadget>
<output>3.5</output>
3.5 km= 3500 m.   Required time = 3500 * 3/125= 
<gadget id="calculator">3500 * 3/125</gadget>
<output>84</output>
84 sec.   Answer:84
<result>C</result>
Two trains are moving in opposite directions at 60 km/hr and 90 km/hr. Their lengths are 2.10 km and 1.4 km respectively. The time taken by the slower train to cross the faster train in seconds is?