A 250m long train is travelling at 30km/hr. Another 200m long train travelling at 40km/hr in the same direction overtakes it. How long would it take to pass the first train completely? Choose the correct option.
A) 2min32secs.	B) 1min32secs.	C) 3min42secs.	D) 2min42secs,	E) 4min12secs.
Relative speed =x-y x,y are their speeds. Distance =(250+200)= 
<gadget id="calculator">(250+200)</gadget>
<output>450</output>
450m Relative speed= (40-30)km/hr =450m =25/9 m/s Time taken to cover 450m = 450*9/25 secs. =162 secs. =2min.42sec. Answer : 2min42secs,
<result>D</result>
A 250m long train is travelling at 30km/hr. Another 200m long train travelling at 40km/hr in the same direction overtakes it. How long would it take to pass the first train completely?