# Problems on Trains- Aptitude Questions and Answers

 A train 100 meters long moving at a speed of 40 km/hr crosses a train 130 meters long coming from the opposite direction in 6 seconds. Find the speed of the second train? A) 98 km/hr B) 96 km/hr C) 94 km/hr D) 90 km/hr Correct Answer : 98 km/hr Explanation :Time taken to cross= 6 sec = 6/3600 sec = 1/600 hr Let the speed of the second train be X km/hr Relative speed = 40 + X km/hr (opposite directions) Distance covered = 100 + 130 = 230 m = 0.23 km Time taken to cross= Distance covered/Relative speed 1/600 = 0.23 / 40 + X 40 + X = 138 X = 98 km/hr A train takes 8 sec to cross a 75 metre long platform at a speed of 90 km/h. What is the length of the train? A) 125 metre B) 150 metre C) 75 metre D) 100 metre Correct Answer : 125 metre Explanation :Let the length of the train be X. Total distance = (X + 75) meters Total time = 8 seconds Speed = 90 km/hr =90 * (5/18) m/s =25 m/s Distance = Speed * Time (X + 75) = 25 * 8 X = 125 Hence, the length of the train is 125 m. A 300 meter long metro train crosses a platform in a metro station in 39 seconds while it crosses a lamp post in 18 seconds. What is the length of the platform? A) 250 meter B) 350 meter C) 520 meter D) 300 meter Correct Answer : 350 meter Explanation :Let, T = Length of Train P = Length of Platform S = Speed of train Time taken to cross the platform = 39 sec Distance = T + P = 300 + P Time = 39 sec Speed, S = (300 + P)/39 m/s............. (1) Time taken to cross a post = 18 sec Distance = T = 300 m Time = 18 sec S = 300/18 = 50/3 m/s Put this value of S in eq(1) we get 50/3 = (300 + P) / 39 300 + P = 650 P = 350 m Length of Platform, P = 350 m