Important Time and Distance Shortcut Tricks for Bank PO, SSC, IBPS

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Today I am going to discuss important concepts and questions for Time and Distance. I am sharing all the important question types for bank exams.
Important Formulas with Tips, Shortcuts and Tricks

FORMULAE:

  1. Speed = Distance/Time
  2. Time = Distance/Speed
  3. Distance = Speed × Time
  4. If the speed of a body is changed in the ratio a : b, then the ratio of the time taken changes in the ratio b : a.
  5. m km/hr = [m × 5/18] m/sec.
  6. m metres/sec = [m × 18/5] km/hr.


Tip 1:  The formula to convert KMPH to MPS and vice versa.

  • km/hr to m/s conversion :  y km/hr = y × (5/18) m/s
  • m/s to km/hr conversion : y m/s = y × (18/5) km/hr
Tip 2: Time taken by a train of length l metres to pass a stationery object of length metres is the time taken by the train to cover (l + b) metres.
Tip 3:  Time taken by a train of length l metres to pass a pole or standing man or a signal post = time taken by the train to cover metres.
* Here “a pole or standing man or a signal post” means object with Zero length.

Tip 4: Two trains or two objects bodies are moving in the same direction at u m/s and v m/s, where u > v, then their relative speed is = (u – v) m/s.

Tip 5: Suppose two trains or two objects bodies are moving in opposite directions at u m/s and v m/s, then their relative speed is = (u + v) m/s.

Tip 6: If two trains of length a metres and b metres are moving in opposite directions at u m/s and v m/s, then the time taken by the trains to cross each other = (a + b)/ (u + v) sec
Tip 7: If two trains of length a metres and b metres are moving in the same direction at u m/s and v m/s, then the time taken by the faster train to cross the slower train =  (a + b)/ (u – v) sec
Tip 8: If two trains start at the same time from points A and B towards each other and after crossing they take ‘a’ and ‘b’ hour in reaching B and A respectively, then:
(A’s speed) : (B’s speed) = Öb : Öa

Tip 9: If a train or a body covers a certain distance at x km/hr and an equal distance at y km/hr. Then, the average speed during the whole journey is 2xy /(x + y) km/hr.

Questions and Answers

Ex. 1. A train 100  m long is running at the speed of 30  km/hr. Find the time taken by it to pass a man standing near the railway line.
Sol. Speed of the train = (30 × 5/18) m/sec = (25/3) m/sec.
Distance moved in passing the standing man = 100  m.
Required time taken = 100/(25/3) = (100 × (3/25)) sec = 12  sec
Ex. 2. A train is moving at a speed of 132 km/hr. If the length of the train is 110 metres, how long will it take to cross a railway platform 165 metres long?
Sol. Speed of train = 132 × (5/18) m/sec = 110/3   m/sec.
Distance covered in passing the platform = (110 + 165) m = 275 m. Time taken =275 × (3/110)  sec =15/2 sec = 7 ½  sec
Ex. 3. A man is standing on a railway bridge which is 180 m long. He finds that a train crosses the bridge in 20 seconds but himself in 8 seconds. Find the length of the train and its speed?
Sol. Let the length of the train be x metres,
Then, the train covers x metres in 8 seconds and (x + 180) metres in 20  sec
x/8 = (x+180)/20
20x = 8 (x +180)
hence x = 120.
Length of the train = 120 m.
Speed of the train = (120/8) m/sec = m/sec = (15 × 18/5) kmph = 54 km
Ex. 4. A train 150 m long is running with a speed of 68 kmph. In what time will it pass a man who is running at 8 kmph in the same direction in which the train is  going?
Sol: Speed of the train relative to man = (68 – 8) kmph
= (60 × 5/18) m/sec = (50/3) m/sec
Time taken by the train to cross   the man
= Time taken by it to cover 150 m at 50/3  m/sec
= 150 × 3/ 50  sec  =  9 sec
Ex. 5. A train 220 m long is running with a speed of 59 kmph. In what  will it pass a man who is running at 7 kmph in the direction opposite to that in which the train is going?
sol. Speed of the train relative to man = (59 + 7) kmph
= (66 × 5/18)  m/sec = 55/3 m/sec.
Time taken by the train to cross the man = Time taken by it to cover 220 m  at (55/3) m/sec
= (220 × 3/55) sec = 12 sec
Ex. 6. Two trains 137 metres and 163 metres in length are running towards each other on parallel lines, one at the rate of 42 kmph and another at 48 kmph. In what   time will they   be clear of each other from the moment they  meet?
Sol. Relative speed of the trains = (42 + 48) kmph = 90 kmph
= (90 × 5/18) m/sec = 25 m/sec.
Time taken by the  trains  to pass each other
= Time taken to cover (137+163) m at 25 m /sec = (300/25) sec = 12  sec
Ex. 7. Two trains 100 metres and 120 metres long are running in the same direction with speeds of  72 km/hr. In how much   time will the first train cross the  second?
Sol: Relative speed of the trains = (72 – 54) km/hr = 18  km/hr
= (18 × 5/18) m/sec = 5 m/sec.
Time taken by the trains to cross each other
= Time taken to cover (100 + 120) m at 5 m /sec = (220/5) sec = 44  sec.
Ex. 8. A train 100 metres long takes 6 seconds to cross a man walking at 5 kmph in the direction  opposite to that of the train. Find the speed of the  train.?
Sol:Let the speed of the train be x kmph.
Speed of the train relative to man = (x+5) kmph = (x+5) × 5/18 m/sec.
Therefore 100/((x+5) × 5/18) = 6
30 (x+5) = 1800
x = 55
Speed of the train is 55 kmph.
Ex. 9. A train running at 54 kmph takes 20 seconds to pass a platform. Next it takes 12 sec   to pass a man walking at 6 kmph in the same direction in which the train is going . Find the length of the train and the length of the platform. 
Sol:Let the length of train be x metres and length of platform be y  metres.
Speed of the train relative to man = (54 – 6) kmph = 48  kmph
= 48 × (5/18) m/sec = 40/3 m/sec.
In passing a man, the train covers its own length with relative speed.
Length of train = (Relative speed * Time)
= ( 40/3) × 12 m = 160 m.
Also, speed of the train = 54 × (5/18) m/sec = 15 m/ sec.
(x+y)/15 = 20
x + y = 300
Y = (300 – 160) m = 140  m.
Ex 10. A man sitting in a train which is travelling at 50 kmph observes that a goods train, travelling in opposite direction, takes 9 seconds to pass him. If the goods train is 280 m long, find its speed?
Sol: Relative speed = 280/9 m / sec = ((280/9) × (18/5)) kmph = 112 kmph.
Speed of goods train = (112 – 50) kmph = 62  kmph.
Ex. 11. Find the time taken by a train 180 m long, running at 72 kmph, in crossing an electric pole.
Sol. Speed of the train = (72 × 5/18) m/sec = 20 m/sec. Distance moved in passing the pole = 180 m.
Required time taken = (180/20) sec = 9 sec.
Ex. 12. A train 140 m long is running at 60 kmph. In how much time will it pass a platform 260 m long?
Sol. Speed of the train = (60 × 5/18) m/sec  = 50/3m/sec.
Distance covered in passing the platform = (140 + 260) m = 400  m
:. Time taken = (400 × 3/50) see = 24 sec.
Ex. 13. A man is standing on a railway bridge which is 180 m long. He finds that a train crosses the bridge in 20 seconds but himself in 8 seconds. Find the length of the train and its speed.
Sol. Let the length of the train be x metres.
Then, the train covers x metres in 8 seconds and (x + 180) metres in 20  seconds.
:. x/8 = (x + 180)/20
20x = 8(x +180)
 x=120
:. Length of train = 120 m.
Speed of train = (120/8) m/sec = 15 m/sec
= 15 × 18/5 Kmph
= 54 Kmph.
Ex. 14. A train 150 m long is running with a speed of 68 kmph. In what time will it pass a man who is running at 8 kmph in the same direction in which the train is going  ?
Sol. Speed of the train relative to man = (68 – 8)  kmph
= (60 × 5/18)m/see = 50/3 m/sec
Time taken by the train to cross the man = Time taken by it to cover 150 m at ( 50/3) m/sec
= (150 × 3/50 ) sec = 9 sec.
Ex. 15. A train 220 m long is running with a speed of 59 kmph. In what time will it pass a man who is running at 7 kmph in the direction opposite to that in which the train is  going?
Sol. Speed of the train relative to man = (59 + 7)  kmph
= (66 × 5/18 ) m/sec = ( 55/3) m/sec.
Time taken by the train to cross the man
:. (x + y)/15 = 20
= x + y = 300
= y = (300 – 160) m =  140m.
:. Length of the platform = 140 m.
Ex. 16. A man sitting in a train which is travelling at 50 kmph observes that a goods train, travelling in opposite direction, takes 9 seconds to pass him. If the goods train is 150 m long, find its speed.
Sol. Relative speed = (150/9) m/sec =(150/9 × 18/5) kmph = 60  kmph.
:. Speed of goods train = (60 – 50) kmph = 10  kmph.
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