Speed, Time and Distance
 A train travelling with uniform speed crosses two bridges of lengths 300 m and 240 m in 21
seconds and 18 seconds respectively. The speed of the train is :

 72 km/hr
 68 km/hr
 65 km/hr
 60 km/hr

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Let the length of the train be x.
∴ Speed of the train = x + 300 = x + 240 21 18 ⇒ x + 300 = x + 240 7 6
⇒ 7x + 1680 = 6x + 1800
⇒ x = 120∴ Speed of the train = x + 300 = 420 = 20 m/sec 21 21 = 20 × 18 kmph = 72 kmph 5 Correct Option: A
Let the length of the train be x.
∴ Speed of the train = x + 300 = x + 240 21 18 ⇒ x + 300 = x + 240 7 6
⇒ 7x + 1680 = 6x + 1800
⇒ x = 120∴ Speed of the train = x + 300 = 420 = 20 m/sec 21 21 = 20 × 18 kmph = 72 kmph 5
 A train, with a uniform speed, crosses a platform, 162 metres long, in 18 seconds and another platform, 120 metres long, in 15 seconds. The speed of the train is

 14 km/hr
 42 km/hr
 50.4 km/hr
 67.2 km/hr

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Let the Length of the train be x
Then, x + 162 = x + 120 18 15
(Speed of the train)⇒ x + 162 = x + 120 6 5
⇒ 6x + 720 = 5x + 810
⇒ x = 810 – 720 = 90∴ Speed of the train = 90 + 162 m/sec. 18 = 252 × 18 kmph 18 5
= 50.4 kmphCorrect Option: C
Let the Length of the train be x
Then, x + 162 = x + 120 18 15
(Speed of the train)⇒ x + 162 = x + 120 6 5
⇒ 6x + 720 = 5x + 810
⇒ x = 810 – 720 = 90∴ Speed of the train = 90 + 162 m/sec. 18 = 252 × 18 kmph 18 5
= 50.4 kmph
 A train with a uniform speed passes a platform, 122 metres long, in 17 seconds and a bridge, 210 metres long, in 25 seconds. The speed of the train is

 46.5 km/hour
 37.5 km/hour
 37.6 km/hour
 39.6 km/hour

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Let the length of the train be x
According to the question,x + 122 = x + 210 17 25
⇒ 25x + 3050 = 17x + 3570
⇒ 25x – 17x = 3570 – 3050
⇒ 8x = 520⇒ x = 520 = 65 metres 8 ∴ Speed of the train = 65 + 122 17 = 187 metre/second 17
= 11 metre/second= 11 × 18 kmph 5
= 39.6 kmphCorrect Option: D
Let the length of the train be x
According to the question,x + 122 = x + 210 17 25
⇒ 25x + 3050 = 17x + 3570
⇒ 25x – 17x = 3570 – 3050
⇒ 8x = 520⇒ x = 520 = 65 metres 8 ∴ Speed of the train = 65 + 122 17 = 187 metre/second 17
= 11 metre/second= 11 × 18 kmph 5
= 39.6 kmph
 A train travelling at a speed of 30 m/sec crosses a platform, 600 metres long, in 30 seconds. The length (in metres) of train is

 120
 150
 200
 300

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Let the length of train be x
According to the question,x + 600 = 30 30
⇒ x + 600 = 900
⇒ x = 900 – 600 = 300 mCorrect Option: D
Let the length of train be x
According to the question,x + 600 = 30 30
⇒ x + 600 = 900
⇒ x = 900 – 600 = 300 m
 A 120 metre long train is running at a speed of 90 km per hour. It will cross a railway platform 230 m long in :


4 4 seconds 5 
9 1 seconds 5  7 seconds
 14 seconds


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Speed of train = 90 kmph
= 90 × 5 = 25 m/sec 18
Distance covered
= 230 + 120 = 350 m∴ Time taken = 350 = 14 seconds 25 Correct Option: D
Speed of train = 90 kmph
= 90 × 5 = 25 m/sec 18
Distance covered
= 230 + 120 = 350 m∴ Time taken = 350 = 14 seconds 25