Two trains of equal length are running on parallel lines in the same direction at 36 km hr and 26 km...........

Explanation:

Let the length of each train be x mts.

Then, distance covered = 2x mts.

Relative speed = 36 - 26 = 10 km/hr.

= 10 x 5/18 = 25/9 m/sec.

2x/36 = 25/9 => x = 50 mts.

Hence, option 4 is the correct answer.