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Problems on Trains ( 11 to 15 ):
APTITUDE QUESTIONS (PROBLEMS ON TRAINS):
11. A train 165 metres long is running with a speed of 60 km/hr. In what time will it pass a man who is running at 6 km/hr in the direction opposite to that in which the train is going?
A) 8 sec
B) 9 sec
C) 7 sec
D) 10 sec
E) None of these
View Answer
Answer: option B
Explanation:
Speed of train relative to man = (60 + 6) km/hr = 66 km/hr = (66*5/18) m/sec = (55/3) m/sec
∴ time taken to pass the man = (165*3/55) sec = 9 sec
12. Two trains 160 m and 190 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time which they take to cross each other, is:
A) 9
B) 9.6
C) 10
D) 12.6
E) None of these
View Answer
Answer: option D
Explanation:
Relative speed = (60 + 40) km/hr = (100*5/18) m/sec = (250/9) m/sec
Distance covered in crossing each other = (160 + 190) m = 350 m
Required time = (350*9/250) sec = 63/5 sec = 12.6 sec
13. A train 110 m long passes a man, running at 6 km/hr in the direction opposite to that of the train, in 6 seconds. The speed of the train is:
A) 54 km/hr
B) 60 km/hr
C) 66 km/hr
D) 72 km/hr
E) None of these
View Answer
Answer: option B
Explanation:
Speed of the train relative to man = (110/6) m/sec = (110/6)*(18/5) km/hr = 66 km/hr
Let the speed of the train be x kmph. Then, relative speed = (x + 6) km/hr
∴ x + 6 = 66 or x = 60 km/hr
14. A 270 metres long train running at the speed of 120 km/hr crosses another train running in opposite direction at the speed of 80 km/hr in 9 seconds. What is the length of the other train?
A) 230 m
B) 250 m
C) 260 m
D) 320 m
E) None of these
View Answer
Answer: option A
Explanation:
Relative speed = (120 + 80) km/hr = (200*5/18) m/sec = (500/9) m/sec
Let the length of the other train be x metres.
Then, (x+270) / 9 = 500/9 <=> x + 270 = 500 <=> x = 230
15. Two trains of equal lengths take 12 seconds and 15 seconds respectively to cross a pole. If the length of each train be 120 metres, in what time will they cross each other travelling in opposite direction?
A) 10
B) 13.3
C) 15
D) 20
E) None of these
View Answer
Answer: option B
Explanation:
Speed of the first train = (120/12) m/sec = 10 m/sec
Speed of the second train = (120/15) m/sec = 8 m/sec
Relative speed = (10 + 8) m/sec = 18 m/sec
∴ required time = (120+120)/18 sec = 13.3 sec