351. How many seconds will a train 120 metre long running at the rate of 36 km/hr take to cross a bridge of 360 metres in length ?

1. 1. 48 sec

   
   
   

   2. 40 sec

   
   
   

   3. 46 sec

   
   
   

   4. 36 sec

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed of train = 36 kmph
   

   =		36 × 5		m/sec.
   		18

   
   = 10 m/sec
   

   Required time =	Length of train and bridge
   	Speed of train

   
   

   =	120 + 360	=	480	= 48 seconds
   	10		10

   Correct Option: A

   Speed of train = 36 kmph
   

   =		36 × 5		m/sec.
   		18

   
   = 10 m/sec
   

   Required time =	Length of train and bridge
   	Speed of train

   
   

   =	120 + 360	=	480	= 48 seconds
   	10		10

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352. If a man running at 15 kmph crosses a bridge in 5 minutes, the length of the bridge is

1. 1. 1000 metres

   
   
   

   2. 500 metres

   
   
   

   3. 750 metres

   
   
   

   4. 1250 metres

   
   
   

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1. View Hint View Answer Discuss in Forum

   Time = 5 minutes
   

   =	1	hour
   	12

   
   ∴  Length of bridge = Speed × Time
   

   = 15 ×	1	=	5	km.
   	12		4

   
   

   =		5	× 1000		metre
   		4

   
   = 1250 metre

   Correct Option: D

   Time = 5 minutes
   

   =	1	hour
   	12

   
   ∴  Length of bridge = Speed × Time
   

   = 15 ×	1	=	5	km.
   	12		4

   
   

   =		5	× 1000		metre
   		4

   
   = 1250 metre

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353. A 200 metre long train is running at a speed of 72 km/hr. How long will it take to cross 800metre long bridge ?

1. 1. 50 seconds

   
   
   

   2. 40 seconds

   
   
   

   3. 60 seconds

   
   
   

   4. 30 seconds

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed of train = 72 kmph
   

   =		72 × 5		m/sec.
   		18

   
   = 20 m/sec.
   

   Required time =	Length of train and bridge
   	Speed of train

   
   

   =	(200 + 800)
   	20

   
   

   =	1000	= 50 seconds
   	20

   Correct Option: A

   Speed of train = 72 kmph
   

   =		72 × 5		m/sec.
   		18

   
   = 20 m/sec.
   

   Required time =	Length of train and bridge
   	Speed of train

   
   

   =	(200 + 800)
   	20

   
   

   =	1000	= 50 seconds
   	20

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

1. 1. 152 m

   
   
   

   2. 125 m

   
   
   

   3. 250 m

   
   
   

   4. 120 m

   
   
   

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1. View Hint View Answer Discuss in Forum

   Length of train = x metre (let)
   

   Speed of train =	(Length of train and bridge)
   	Time taken in crossing

   
   

   ⇒	x + 500	=	x + 250
   	100		60

   
   

   ⇒	x + 500	=	x + 250
   	5		3

   
   ⇒  5x + 1250 = 3x + 1500
   ⇒  5x – 3x = 1500 – 1250
   ⇒  2x = 250
   

   ⇒  x =	250	= 125 metre
   	2

   Correct Option: B

   Length of train = x metre (let)
   

   Speed of train =	(Length of train and bridge)
   	Time taken in crossing

   
   

   ⇒	x + 500	=	x + 250
   	100		60

   
   

   ⇒	x + 500	=	x + 250
   	5		3

   
   ⇒  5x + 1250 = 3x + 1500
   ⇒  5x – 3x = 1500 – 1250
   ⇒  2x = 250
   

   ⇒  x =	250	= 125 metre
   	2

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355. A train 150 metre long takes 20 seconds to cross a platform 450 metre long. The speed of the train in, km per hour, is :

1. 1. 108

   
   
   

   2. 100

   
   
   

   3. 106

   
   
   

   4. 104

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed of train =	length of platform and train
   	Time taken in crossing

   
   

   =		450 + 150		m/sec.
   		20

   
   

   =		600		m/sec.
   		20

   
   

   =		30 ×	18		kmph
   			5

   
   = 108 kmph.

   Correct Option: A

   Speed of train =	length of platform and train
   	Time taken in crossing

   
   

   =		450 + 150		m/sec.
   		20

   
   

   =		600		m/sec.
   		20

   
   

   =		30 ×	18		kmph
   			5

   
   = 108 kmph.

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