At what time will the train reach city X from city Y? I. The train crosses another train of equal length of 200 metres and running in opposite directions in 15 seconds. II. The train leaves city Y at 7.15 a.m. for city X situated at a distance of 558 km. III. The 200 metres long train crosses a signal pole in 10 seconds.

All I, II and III are required.

What is the length of a running train P crossing another running train Q? I. These two trains take 18 seconds to cross each other. II. These trains are running in opposite directions. III. The length of the train Q is 180 metres.

Even with I, II and III, the answer cannot be obtained.

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.

I alone sufficient while II alone not sufficient to answer

II alone sufficient while I alone not sufficient to answer

Either I or II alone sufficient to answer

Both I and II are not sufficient to answer

Both I and II are necessary to answer

What is the length of a running train crossing another 180 metre long train running in the opposite direction? I. The relative speed of the two trains was 150 kmph. II. The trains took 9 seconds to cross each other.

I alone sufficient while II alone not sufficient to answer

II alone sufficient while I alone not sufficient to answer

Either I or II alone sufficient to answer

Both I and II are not sufficient to answer

Both I and II are necessary to answer

What is the length of a running train? I. The train crosses a man in 9 seconds. II. The train crosses a 240 metre long platform in 24 seconds.

I alone sufficient while II alone not sufficient to answer

II alone sufficient while I alone not sufficient to answer

Either I or II alone sufficient to answer

Both I and II are not sufficient to answer

Both I and II are necessary to answer

What is the speed of a train if it overtakes two persons who are walking in the same direction at the rate of am/s and (a + 1) m/s and passes them completely in b seconds and (b + 1) seconds respectively?

$\frac{{2{\text{a}} + 1}}{2}$$ m/s

49 + Mcqs in Problems on Trains in General Aptitude Page 1 McqOptions

1.	A train travelling at a speed of 75 mph enters a tunnel 3 miles long. The train is mile long. How long does it take for the train to pass through the tunnel from the moment the front enters to the moment the rear emerges?
A.	2.5 min
B.	3 min
C.	3.2 min
D.	3.5 min
Answer» C. 3.2 min

Discussion

2.	At what time will the train reach city X from city Y? I. The train crosses another train of equal length of 200 metres and running in opposite directions in 15 seconds. II. The train leaves city Y at 7.15 a.m. for city X situated at a distance of 558 km. III. The 200 metres long train crosses a signal pole in 10 seconds.
A.	I only
B.	II only
C.	III only
D.	II and III only
E.	All I, II and III are required.
Answer» E. All I, II and III are required.

Discussion

3.	What is the length of a running train P crossing another running train Q? I. These two trains take 18 seconds to cross each other. II. These trains are running in opposite directions. III. The length of the train Q is 180 metres.
A.	I only
B.	II only
C.	III only
D.	All I, II and III are required
E.	Even with I, II and III, the answer cannot be obtained.
Answer» F.

Discussion

4.	What is the speed of the train?_x000D_ I. _x000D_ The train crosses a signal pole in 18 seconds._x000D_ II. _x000D_ The train crosses a platform of equal length in 36 seconds._x000D_ III. _x000D_ Length of the train is 330 metres.
A.	I and II only
B.	II and III only
C.	I and III only
D.	III and either I or II only
E.	Any two of the three
Answer» E. Any two of the three

Discussion

5.	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.
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
Answer» F.

Discussion

6.	What is the speed of the train?_x000D_ I. _x000D_ The train crosses a tree in 13 seconds._x000D_ II. _x000D_ The train crosses a platform of length 250 metres in 27 seconds._x000D_ III. _x000D_ The train crosses another train running in the same direction in 32 seconds.
A.	I and II only
B.	II and III only
C.	I and III only
D.	Any two of the three
E.	None of these
Answer» B. II and III only

Discussion

7.	What is the length of a running train crossing another 180 metre long train running in the opposite direction? I. The relative speed of the two trains was 150 kmph. II. The trains took 9 seconds to cross each other.
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
Answer» F.

Discussion

8.	What is the length of a running train? I. The train crosses a man in 9 seconds. II. The train crosses a 240 metre long platform in 24 seconds.
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
Answer» F.

Discussion

9.	Two identical trains A and B running in opposite directions at same speed take 2 minutes to cross each other completely. The number of bogies of A are increased from 12 to 16. How much more time would they now require to cross each other?
A.	0 sec
B.	0 sec
C.	0 sec
D.	0 sec
Answer» B. 0 sec

Discussion

10.	Two trains, 130 and 110 meters long, are going in the same direction. The faster train takes one minute to pass the other completely. If they are moving in opposite directions, they pass each other completely in 3 seconds. Find the speed of the faster train.
A.	8 m/sec
B.	2 m/sec
C.	6 m/sec
D.	0 m/sec
Answer» C. 6 m/sec

Discussion

11.	A man standing on a platform finds that a train takes 3 seconds to pass him and another train of the same length moving in the opposite direction takes 4 seconds. The time taken by the trains to pass each other will be :
A.	$2\frac{3}{7}$$ seconds
B.	$3\frac{3}{7}$$ seconds
C.	$4\frac{3}{7}$$ seconds
D.	$5\frac{3}{7}$$ seconds
Answer» C. $4\frac{3}{7}$$ seconds

Discussion

12.	A 150 m long train crosses a milestone in 15 seconds and a train of same length coming from the opposite direction in 12 seconds. The speed of the other train is?
A.	6 kmph
B.	5 kmph
C.	0 kmph
D.	4 kmph
Answer» E.

Discussion

13.	Two trains are running in opposite directions with the same speed. If the length of each train is 120 meters and they cross each other in 12 seconds, then the speed of each train (in km/hr) is?
A.	0 km/hr
B.	8 km/hr
C.	2 km/hr
D.	6 km/hr
Answer» E.

Discussion

14.	A train 75 m long overtook a person who was walking at the rate of 6 km/hr in the same direction and passed him in $$7\frac{1}{2}$$ seconds. Subsequently, it overtook a second person and passed him in $$6\frac{3}{4}$$ seconds. At what rate was the second person travelling?
A.	km/hr
B.	km/hr
C.	km/hr
D.	km/hr
Answer» C. km/hr

Discussion

15.	A train 125 m long passes a man, running at 5 kmph in the same direction in which the train is going, in 10 seconds. The speed of the train is:
A.	5 km/hr
B.	0 km/hr
C.	4 km/hr
D.	5 km/hr
Answer» C. 4 km/hr

Discussion

16.	A train with 90 km/hr crosses a bridge in 36 seconds. Another train 100 meters shorter crosses the same bridge at 45 km/hr. What is the time taken by the second train to cross the bridge?
A.	1 seconds
B.	2 seconds
C.	3 seconds
D.	4 seconds
Answer» E.

Discussion

17.	Two trains 200 meters and 150 meters long are running on parallel rails in the same direction at speed of 40 km/hr and 45 km/hr respectively. Time taken by the faster train to cross the slowed train will be:
A.	2 seconds
B.	32 seconds
C.	92 seconds
D.	52 seconds
Answer» E.

Discussion

18.	The time taken by a train 180 m long, travelling at 42 kmph, in passing a person walking in the same direction at 6 kmph, will be
A.	8 sec
B.	1 sec
C.	4 sec
D.	5 sec
Answer» B. 1 sec

Discussion

19.	A train speeds past a pole in 20 seconds and speeds past a platform 100 meters in length in 30 seconds. What is the length of the train?
A.	00 meters
B.	50 meters
C.	80 meters
D.	00 meters
Answer» E.

Discussion

20.	A train takes 5 minutes to cross a telegraphic post. Then the time taken by another train whose length is just double of the first train and moving with same speed to cross a platform of its own length is :
A.	0 minutes
B.	5 minutes
C.	0 minutes
D.	ata inadequate
Answer» D. ata inadequate

Discussion

21.	A 50 meter long train passes over a bridge at the speed of 30 km per hour. If it takes 36 seconds to cross the bridge, what is the length of the bridge?
A.	00 meters
B.	50 meters
C.	00 meters
D.	50 meters
Answer» C. 00 meters

Discussion

22.	A 120 meter long train is running at a speed of 90 km/hr. It will cross a railway platform 230 m long in :
A.	seconds
B.	seconds
C.	2 seconds
D.	4 seconds
Answer» E.

Discussion

23.	A man sitting in a train is counting the pillars of electricity. The distance between two pillars is 60 meters, and the speed of the train is 42 km/hr. In 5 hours, how many pillars will he count?
A.	501
B.	600
C.	800
D.	one of these
Answer» B. 600

Discussion

24.	Two trains of equal lengths takes 10 seconds and 15 seconds respectively to cross a telegraph post. If the length of each train be 120 miters, in what time ( in seconds) will they cross each other traveling in opposite direction?
A.	0
B.	2
C.	5
D.	0
Answer» C. 5

Discussion

25.	Two trains of equal length are running on parallel lines in the same directions at 46 km/hr and 36 km/hr. The faster train passes the slower train in 36 seconds. The length of each train is?
A.	0 m
B.	2 m
C.	0 m
D.	2 m
Answer» B. 2 m

Discussion

26.	A train, 240 m long, crosses a man walking alone the line in opposite direction at the rate of 3 kmph in 10 seconds. The speed of the train is?
A.	3 kmph
B.	5 kmph
C.	3.4 kmph
D.	6.4 kmph
Answer» D. 6.4 kmph

Discussion

27.	Two trains are coming from opposite directions with speed of 75 km/hr and 100 km/hr on to parallel tracks. At some moment the distance between them is 100km. After T hours, distance between them is again 100 km. T is equal to?
A.	hr
B.	$1\frac{1}{7}$$ hr
C.	$1\frac{1}{2}$$ hr
D.	hr
Answer» C. $1\frac{1}{2}$$ hr

Discussion

28.	A train 360 m long is running at a speed of 45 km/hr. In what time will it pass a bridge 140 m long?
A.	0 sec
B.	2 sec
C.	5 sec
D.	8 sec
Answer» B. 2 sec

Discussion

29.	A train moves with a speed of 30 kmph for 12 minutes and for next 8 minutes at a speed of 45 kmph. Find the average speed of the train?
A.	7.50 kmph
B.	6 kmph
C.	8 kmph
D.	0 kmph
Answer» C. 8 kmph

Discussion

30.	A train which is moving at an average speed of 40 km/h reaches its destination on time. When its average speed reduces to 35 km/h, then it reaches its destination 15 minutes late. The distance traveled by the train is?
A.	0 km
B.	0 km
C.	0 km
D.	0 km
Answer» B. 0 km

Discussion

31.	Train A traveling at 63 kmph can cross a platform 199.5 m long in 21 seconds. How much would train A take to completely cross (from the moment they meet ) train B, 157 m long and traveling at 54 kmph in opposite direction which train A is traveling? (in seconds)
A.	6
B.	8
C.	2
D.	0
Answer» E.

Discussion

32.	Train A passes a lamp post in 9 seconds and 700 meter long platform in 30 seconds. How much time will the same train take to cross a platform which is 800 meters long? (in seconds)
A.	2 seconds
B.	1 seconds
C.	3 seconds
D.	0 seconds
Answer» D. 0 seconds

Discussion

33.	A train starts from A at 7 a.m. towards B with speed 50 km/h. Another train starts from B at 8 a.m. with speed of 60 km/h towards A. Both of them meet at 10 a.m. at C. The ratio of the distance AC to BC is?
A.	: 6
B.	: 4
C.	: 5
D.	: 5
Answer» C. : 5

Discussion

34.	A train moving at a rate of 36 km/hr crosses a standing man in 10 seconds. It will cross a platform 55 meters long in?
A.	second
B.	second
C.	$15\frac{1}{2}$$ second
D.	$5\frac{1}{2}$$ second
Answer» D. $5\frac{1}{2}$$ second

Discussion

35.	A train passes by a lamp post at platformin 7 sec. and passes by the platform completely in 28 sec. If the length of the platform is 390m, then length of the train (in meters) is?
A.	20 m
B.	30 m
C.	40 m
D.	50 m
Answer» C. 40 m

Discussion

36.	Two trains, A ans B start from stations X and Y towards each other, they take 4 hours 48 minutes and 3 hours 20 minutes to reach Y and X respectively after they meet. If train A is moving at 45 km/hr, then the speed of the train B is?
A.	0 km/hr
B.	4.80 km/hr
C.	4 km/hr
D.	7.5 km/hr
Answer» D. 7.5 km/hr

Discussion

37.	Two trains start simultaneously (with uniform speeds) from two stations 270 km apart, each to the opposite station; they reach their destinations in $$6\frac{1}{4}$$ hours and 4 hours after they meet. The rate at which the slower train travels is :
A.	6 km/hr
B.	4 km/hr
C.	5 km/hr
D.	0 km/hr
Answer» C. 5 km/hr

Discussion

38.	Two trains 180 meters and 120 meters in length are running towards each other on parallel tracks, one at the rate 65 km/hr and another at 55 km/hr. In how many seconds will they be cross each other from the moment they meet?
A.	seconds
B.	seconds
C.	2 seconds
D.	5 seconds
Answer» C. 2 seconds

Discussion

39.	Two trains start at the same time from A and B and proceed toward each other at the sped of 75 km/hr and 50 km/hr respectively. When both meet at a point in between, one train was found to have traveled 175 km more then the other. Find the distance between A and B?
A.	75 km
B.	85 km
C.	58 km
D.	57 km
Answer» B. 85 km

Discussion

40.	A train takes 9 sec to cross a pole. If the speed of the train is 48 kmph, then length of the train is?
A.	50 m
B.	20 m
C.	0 m
D.	0 m
Answer» C. 0 m

Discussion

41.	Two trains start at the same time for two station A and B toward B and A respectively. If the distance between A and B is 220 km and their speeds are 50 km/hr and 60 km/hr respectively then after how much time will they meet each other?
A.	hr
B.	$2\frac{1}{2}$$ hr
C.	hr
D.	hr
Answer» B. $2\frac{1}{2}$$ hr

Discussion

42.	A train cover a distance of 3584 km in 2 days 8 hours. If it covers 1440 km on the first day and 1608 km on the second day, by how much does the average speed of the train for the remaining part of the journey differ from that for the entire journey?
A.	km/h
B.	km/h
C.	0 km/h
D.	km/h
Answer» B. km/h

Discussion

43.	Train A passes a lamp post in 3 seconds and 900 meter long platform in 30 seconds. How much time will the same train take to cross a platform which is 800 meters long? (in seconds)
A.	4 seconds
B.	7 seconds
C.	3 seconds
D.	7 seconds
Answer» E.

Discussion

44.	A train passes two bridges of length 500 m and 250 m in 100 seconds and 60 seconds respectively. The length of the train is?
A.	52 m
B.	25 m
C.	50 m
D.	20 m
Answer» C. 50 m

Discussion

45.	Two train 100 meters and 95 meters long respectively pass each other in 27 seconds, when they run in the same direction and in 9 seconds when they run in opposite directions. Speed of the two trains are?
A.	4 km/hr, 22 km/hr
B.	2 km/hr, 26 km/hr
C.	6 km/hr, 18 km/hr
D.	0 km/hr, 20 km/hr
Answer» C. 6 km/hr, 18 km/hr

Discussion

46.	A train of length 500 feet crosses a platform of length 700 feet in 10 seconds. The speed of the train is?
A.	0 ft/second
B.	5 ft/second
C.	00 ft/second
D.	20 ft/second
Answer» E.

Discussion

47.	A train is moving at a speed of 132 km/hr. If the length of the train is 110 meters, how long it will take to cross a railway platform 165 meter long?
A.	second
B.	.5 second
C.	0 second
D.	5 second
Answer» C. 0 second

Discussion

48.	A train passes a 50 meter long platform in 14 seconds and a man standing on platform 10 seconds.The speed of the train is?
A.	4 km/hr
B.	6 km/hr
C.	0 km/hr
D.	5 km/hr
Answer» E.

Discussion

49.	What is the speed of a train if it overtakes two persons who are walking in the same direction at the rate of am/s and (a + 1) m/s and passes them completely in b seconds and (b + 1) seconds respectively?
A.	a + b) m/s
B.	a + b + 1) m/s
C.	2a + 1) m/s
D.	$\frac{{2{\text{a}} + 1}}{2}$$ m/s
Answer» C. 2a + 1) m/s

Discussion

Explore topic-wise MCQs in General Aptitude.

A train travelling at a speed of 75 mph enters a tunnel 3 miles long. The train is mile long. How long does it take for the train to pass through the tunnel from the moment the front enters to the moment the rear emerges?

What is the length of a running train P crossing another running train Q? I. These two trains take 18 seconds to cross each other. II. These trains are running in opposite directions. III. The length of the train Q is 180 metres.

What is the speed of the train?_x000D_ I. _x000D_ The train crosses a signal pole in 18 seconds._x000D_ II. _x000D_ The train crosses a platform of equal length in 36 seconds._x000D_ III. _x000D_ Length of the train is 330 metres.

What is the speed of the train?_x000D_ I. _x000D_ The train crosses a tree in 13 seconds._x000D_ II. _x000D_ The train crosses a platform of length 250 metres in 27 seconds._x000D_ III. _x000D_ The train crosses another train running in the same direction in 32 seconds.

What is the length of a running train crossing another 180 metre long train running in the opposite direction? I. The relative speed of the two trains was 150 kmph. II. The trains took 9 seconds to cross each other.

What is the length of a running train? I. The train crosses a man in 9 seconds. II. The train crosses a 240 metre long platform in 24 seconds.

Two identical trains A and B running in opposite directions at same speed take 2 minutes to cross each other completely. The number of bogies of A are increased from 12 to 16. How much more time would they now require to cross each other?

Two trains, 130 and 110 meters long, are going in the same direction. The faster train takes one minute to pass the other completely. If they are moving in opposite directions, they pass each other completely in 3 seconds. Find the speed of the faster train.

A man standing on a platform finds that a train takes 3 seconds to pass him and another train of the same length moving in the opposite direction takes 4 seconds. The time taken by the trains to pass each other will be :

A 150 m long train crosses a milestone in 15 seconds and a train of same length coming from the opposite direction in 12 seconds. The speed of the other train is?

Two trains are running in opposite directions with the same speed. If the length of each train is 120 meters and they cross each other in 12 seconds, then the speed of each train (in km/hr) is?

A train 75 m long overtook a person who was walking at the rate of 6 km/hr in the same direction and passed him in $$7\frac{1}{2}$$ seconds. Subsequently, it overtook a second person and passed him in $$6\frac{3}{4}$$ seconds. At what rate was the second person travelling?

A train 125 m long passes a man, running at 5 kmph in the same direction in which the train is going, in 10 seconds. The speed of the train is:

A train with 90 km/hr crosses a bridge in 36 seconds. Another train 100 meters shorter crosses the same bridge at 45 km/hr. What is the time taken by the second train to cross the bridge?

Two trains 200 meters and 150 meters long are running on parallel rails in the same direction at speed of 40 km/hr and 45 km/hr respectively. Time taken by the faster train to cross the slowed train will be:

The time taken by a train 180 m long, travelling at 42 kmph, in passing a person walking in the same direction at 6 kmph, will be

A train speeds past a pole in 20 seconds and speeds past a platform 100 meters in length in 30 seconds. What is the length of the train?

A train takes 5 minutes to cross a telegraphic post. Then the time taken by another train whose length is just double of the first train and moving with same speed to cross a platform of its own length is :

A 50 meter long train passes over a bridge at the speed of 30 km per hour. If it takes 36 seconds to cross the bridge, what is the length of the bridge?

A 120 meter long train is running at a speed of 90 km/hr. It will cross a railway platform 230 m long in :

A man sitting in a train is counting the pillars of electricity. The distance between two pillars is 60 meters, and the speed of the train is 42 km/hr. In 5 hours, how many pillars will he count?

Two trains of equal lengths takes 10 seconds and 15 seconds respectively to cross a telegraph post. If the length of each train be 120 miters, in what time ( in seconds) will they cross each other traveling in opposite direction?

Two trains of equal length are running on parallel lines in the same directions at 46 km/hr and 36 km/hr. The faster train passes the slower train in 36 seconds. The length of each train is?

A train, 240 m long, crosses a man walking alone the line in opposite direction at the rate of 3 kmph in 10 seconds. The speed of the train is?

Two trains are coming from opposite directions with speed of 75 km/hr and 100 km/hr on to parallel tracks. At some moment the distance between them is 100km. After T hours, distance between them is again 100 km. T is equal to?

A train 360 m long is running at a speed of 45 km/hr. In what time will it pass a bridge 140 m long?

A train moves with a speed of 30 kmph for 12 minutes and for next 8 minutes at a speed of 45 kmph. Find the average speed of the train?

A train which is moving at an average speed of 40 km/h reaches its destination on time. When its average speed reduces to 35 km/h, then it reaches its destination 15 minutes late. The distance traveled by the train is?

Train A traveling at 63 kmph can cross a platform 199.5 m long in 21 seconds. How much would train A take to completely cross (from the moment they meet ) train B, 157 m long and traveling at 54 kmph in opposite direction which train A is traveling? (in seconds)

Train A passes a lamp post in 9 seconds and 700 meter long platform in 30 seconds. How much time will the same train take to cross a platform which is 800 meters long? (in seconds)

A train starts from A at 7 a.m. towards B with speed 50 km/h. Another train starts from B at 8 a.m. with speed of 60 km/h towards A. Both of them meet at 10 a.m. at C. The ratio of the distance AC to BC is?

A train moving at a rate of 36 km/hr crosses a standing man in 10 seconds. It will cross a platform 55 meters long in?

A train passes by a lamp post at platformin 7 sec. and passes by the platform completely in 28 sec. If the length of the platform is 390m, then length of the train (in meters) is?

Two trains, A ans B start from stations X and Y towards each other, they take 4 hours 48 minutes and 3 hours 20 minutes to reach Y and X respectively after they meet. If train A is moving at 45 km/hr, then the speed of the train B is?

Two trains start simultaneously (with uniform speeds) from two stations 270 km apart, each to the opposite station; they reach their destinations in $$6\frac{1}{4}$$ hours and 4 hours after they meet. The rate at which the slower train travels is :

Two trains 180 meters and 120 meters in length are running towards each other on parallel tracks, one at the rate 65 km/hr and another at 55 km/hr. In how many seconds will they be cross each other from the moment they meet?

Two trains start at the same time from A and B and proceed toward each other at the sped of 75 km/hr and 50 km/hr respectively. When both meet at a point in between, one train was found to have traveled 175 km more then the other. Find the distance between A and B?

A train takes 9 sec to cross a pole. If the speed of the train is 48 kmph, then length of the train is?

Two trains start at the same time for two station A and B toward B and A respectively. If the distance between A and B is 220 km and their speeds are 50 km/hr and 60 km/hr respectively then after how much time will they meet each other?

A train cover a distance of 3584 km in 2 days 8 hours. If it covers 1440 km on the first day and 1608 km on the second day, by how much does the average speed of the train for the remaining part of the journey differ from that for the entire journey?

Train A passes a lamp post in 3 seconds and 900 meter long platform in 30 seconds. How much time will the same train take to cross a platform which is 800 meters long? (in seconds)

A train passes two bridges of length 500 m and 250 m in 100 seconds and 60 seconds respectively. The length of the train is?

Two train 100 meters and 95 meters long respectively pass each other in 27 seconds, when they run in the same direction and in 9 seconds when they run in opposite directions. Speed of the two trains are?

A train of length 500 feet crosses a platform of length 700 feet in 10 seconds. The speed of the train is?

A train is moving at a speed of 132 km/hr. If the length of the train is 110 meters, how long it will take to cross a railway platform 165 meter long?

A train passes a 50 meter long platform in 14 seconds and a man standing on platform 10 seconds.The speed of the train is?

What is the speed of a train if it overtakes two persons who are walking in the same direction at the rate of am/s and (a + 1) m/s and passes them completely in b seconds and (b + 1) seconds respectively?