# If one train m long, the length of other train is :

Two trains running in opposite directions at 36 kmph and 45 kmph cross each other in 20 seconds. If one train 200 m long, the length of other train is

- 200 m.
- 144 m.
- 250 m.
- 240 m.

Solution: Question is incomplete if we take first train length 200 m then the respective speed of both trains in opposite side will be (36+45)=81 Km/h **Speed =81 x 5/18**** =45/2 m/sec **** If both trains cross each other in 20 secs then total length of both trains (Distance)= Speed X Time **** =45/2X20 =450 m then the length of another train=450-200=250 m**** So option (3) will be correct.**

**Answer: (3) 250 m**

**Explanation:-
**Let the length of another train be X m.

The respective speed of both trains in opposite side = 36 + 45

= 81 km/hr

Speed in m/sec = 81 x 5/18

= 9 x 5/2

= 45/2 m/sec

If both trains cross each other in 20 sec

Then, total length of both trains = 45 x 20/2 = (X + 200)

900/2 = X + 200

X = 450 – 200

X = 250 m

Then, the length of another train is 250 m.

Hence, correct answer is option (3) 250 m.