Home / Arithmetic Aptitude / Problems on Trains :: Discussion

### Discussion :: Problems on Trains

1.  What is the speed of the train whose length is 210 metres?

I. The train crosses another train (Howrah Express/12869) of 300 metres length running in opposite direction in 10 seconds.

II. The train crosses another train (Howrah Express/12869) running in the same direction at the speed of 60 km/hr in 30 seconds.

2. A.

I alone sufficient while II alone not sufficient to answer

B.

II alone sufficient while I alone not sufficient to answer

C.

Either I or II alone sufficient to answer

D.
 Both I and II are not sufficient to answer
E.

Both I and II are necessary to answer

Explanation :

 Time taken to cross the train, running in opposite directions = $$\frac { (l1+l2) } { (u+v) } sec$$

 10 = $$\frac { (210+300) } { (u+v) }$$

u + v = 51.

 Time taken to cross the train, running in same direction = $$\frac { (l1+l2) } { (u-v) } sec$$sec.

 30 = $$\frac { (210+300) } { ((u-60) \times(5/8))} sec$$

 u = $$(17+\frac{50}{3})m/sec$$ Thus, u and v can be obtained.