346. A is twice as fast as B and B is thrice as fast as C is. The journey

     covered by C in 1	1	hours will be covered by A in
     	2

1. 1. 15 minutes

   
   
   

   2. 20 minutes

   
   
   

   3. 30 minutes

   
   
   

   4. 1 hour

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed of B = x kmph (let)
   Speed of A = 2x kmph
   

   Speed of C =	x	kmph
   	3

   
   

   ∴	Speed of A	=	2x	= 6
   	Speed of C		(x/3)

   
   

   ∴  Required time =	1	of	3	hours
   	6		2

   
   

   =	1	hour = 15 minutes
   	4

   Correct Option: A

   Speed of B = x kmph (let)
   Speed of A = 2x kmph
   

   Speed of C =	x	kmph
   	3

   
   

   ∴	Speed of A	=	2x	= 6
   	Speed of C		(x/3)

   
   

   ∴  Required time =	1	of	3	hours
   	6		2

   
   

   =	1	hour = 15 minutes
   	4

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347. A truck travels at 90 km/hr for

     the first 1	1	hours. After that it travels at 70 km/hr.
     	2

     Find the time taken by the truck to travel 310 kilometres.

1. 1. 2.5 hrs

   
   
   

   2. 3 hrs

   
   
   

   3. 3.5 hrs

   
   
   

   4. 4 hrs

   
   
   

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1. View Hint View Answer Discuss in Forum

   Distance covered by truck in	3	hours
   	2

   
   = Speed × Time
   

   = 90 ×	3	= 135 km
   	2

   
   Remaining distance
   = 310 – 135 = 175 km
   ∴  Time taken at 70 kmph
   

   =	175	= 2.5 hours
   	70

   
   ∴  Total time = 1.5 + 2.5 = 4 hours

   Correct Option: D

   Distance covered by truck in	3	hours
   	2

   
   = Speed × Time
   

   = 90 ×	3	= 135 km
   	2

   
   Remaining distance
   = 310 – 135 = 175 km
   ∴  Time taken at 70 kmph
   

   =	175	= 2.5 hours
   	70

   
   ∴  Total time = 1.5 + 2.5 = 4 hours

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348. The lengths of a train and that of a platform are equal. If with a speed of 90 km/hr the train
     crosses the platform in one minute, then the length of the train (in metres) is

1. 1. 500

   
   
   

   2. 600

   
   
   

   3. 750

   
   
   

   4. 900

   
   
   

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1. View Hint View Answer Discuss in Forum

   Let, length of train = length of platform = x metre
   Speed of train = 90 kmph
   

   =		90 × 5		m/sec.
   		18

   
   = 25 m/sec.
   

   ∴  Speed of train =	Length of platform and train
   	Time taken in crossing

   
   

   ⇒  25 =	2x	⇒ 2x = 25 × 60
   	60

   
   

   ⇒  x =	25 × 60	= 750 metre
   	2

   Correct Option: C

   Let, length of train = length of platform = x metre
   Speed of train = 90 kmph
   

   =		90 × 5		m/sec.
   		18

   
   = 25 m/sec.
   

   ∴  Speed of train =	Length of platform and train
   	Time taken in crossing

   
   

   ⇒  25 =	2x	⇒ 2x = 25 × 60
   	60

   
   

   ⇒  x =	25 × 60	= 750 metre
   	2

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349. A train 50 metres long passes a platform of length 100 metres in 10 seconds. The speed of the train in metre/second is

1. 1. 50

   
   
   

   2. 10

   
   
   

   3. 15

   
   
   

   4. 20

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed of train =	Length of (train + platform)
   	Time taken to crossing

   
   

   =	(50 + 100)
   	10

   
   

   =	150	= 15 m/sec
   	10

   Correct Option: C

   Speed of train =	Length of (train + platform)
   	Time taken to crossing

   
   

   =	(50 + 100)
   	10

   
   

   =	150	= 15 m/sec
   	10

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350. A train 50 metre long passes a platform 100 metre long in 10 seconds. The speed of the train in km/hr is

1. 1. 10

   
   
   

   2. 54

   
   
   

   3. 15

   
   
   

   4. 100

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed of train =	Length of platform and train
   	Time taken to crossing

   
   

   =		100 + 50		metre/second
   		10

   
   = 15 metre/second
   

   =		15 ×	18		kmph
   			5

   
   = 54 kmph

   Correct Option: B

   Speed of train =	Length of platform and train
   	Time taken to crossing

   
   

   =		100 + 50		metre/second
   		10

   
   = 15 metre/second
   

   =		15 ×	18		kmph
   			5

   
   = 54 kmph

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