331. Sarita and Julie start walking from the same place in the opposite directions. If Julie walks at a

     speed of 2	1	km/hr and Sarita at a speed
     	2

     of 2 km/hr, in how much time will they be 18 km apart ?

1. 1. 4.0 hrs

   
   
   

   2. 4.5 hrs

   
   
   

   3. 5.0 hrs

   
   
   

   4. 4.8 hrs

   
   
   

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1. View Hint View Answer Discuss in Forum

   =		5	+ 2		kmph =	9	kmph
   		2				2

   Time =	Distance	=	18
   	Relative speed		(9/2)

   
   

   =	18 × 2	= 4 hours
   	9

   Correct Option: A

   =		5	+ 2		kmph =	9	kmph
   		2				2

   Time =	Distance	=	18
   	Relative speed		(9/2)

   
   

   =	18 × 2	= 4 hours
   	9

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332. A train covers a distance of 10 km in 12 minutes. If its speed is decreased by 5 km/hr, the time taken by it to cover the same distance will be :

1. 1. 10 minutes

   
   
   

   2. 13 minutes 20 sec

   
   
   

   3. 13 minutes

   
   
   

   4. 11 minutes 20 sec

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed of train =	Distance
   	Time

   
   

   =	10	kmph
   	(12/60)

   
   

   =	10 × 60	= 50 kmph
   	12

   
   New speed = 45 kmph
   

   ∴  Required time =	10	hour
   	45

   
   

   =	2	× 60 minutes
   	9

   
   

   =	40	minutes
   	3

   
   = 13 minutes 20 seconds

   Correct Option: B

   Speed of train =	Distance
   	Time

   
   

   =	10	kmph
   	(12/60)

   
   

   =	10 × 60	= 50 kmph
   	12

   
   New speed = 45 kmph
   

   ∴  Required time =	10	hour
   	45

   
   

   =	2	× 60 minutes
   	9

   
   

   =	40	minutes
   	3

   
   = 13 minutes 20 seconds

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333. A man walks ‘a’ km in ‘b’ hours. The time taken to walk 200 metres is

1. 1. 200b	hours
      a

   
   
   

   2. b	hours
      5a

   
   
   

   3. b	hours
      a

   
   
   

   4. ab	hours
      200

   
   
   

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1. View Hint View Answer Discuss in Forum

   Man’s speed =	Distance
   	Time

   
   

   =	a	kmph
   	b

   
   

   =	1000a	m/hour
   	b

   
   ∴  Time taken in walking 200 metre
   

   =	200	=	b	hours
   	1000a/b		5a

   Correct Option: B

   Man’s speed =	Distance
   	Time

   
   

   =	a	kmph
   	b

   
   

   =	1000a	m/hour
   	b

   
   ∴  Time taken in walking 200 metre
   

   =	200	=	b	hours
   	1000a/b		5a

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334. The speed 3	1	m/sec when expressed
     	3

     in km/hour becomes

1. 1. 8

   
   
   

   2. 9

   
   
   

   3. 10

   
   
   

   4. 12

   
   
   

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1. View Hint View Answer Discuss in Forum

   ∵  1 m/sec =	18	kmph
   	5

   
   

   ∴	10	m/sec
   	3

   
   

   =	18	×	10	= 12 kmph
   	5		3

   Correct Option: D

   ∵  1 m/sec =	18	kmph
   	5

   
   

   ∴	10	m/sec
   	3

   
   

   =	18	×	10	= 12 kmph
   	5		3

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335. A train covers a certain distance in 210 minutes at a speed of 60 kmph. The time taken by the train, to cover the same distance at a speed of 80 kmph is :

1. 1. 3	5	hours
      	8

   
   
   

   2. 2	5	hours
      	8

   
   
   

   3. 4	5	hours
      	8

   
   
   

   4. 3 hours

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed of train = 60 kmph
   Time = 210 minutes
   

   =	210	hours
   	60

   
   

   or	7	hours
   	2

   
   

   Distance covered = 60 ×	7	= 210 km
   	2

   
   

   Time taken at 80 kmph =	210	=	21	hours
   	80		8

   
   

   = 2	5	hours
   	8

   
   
   Second Method :
   

   Here, S1 60, t1 =	210	hrs
   	60

   
   S₂ = 80, t₂ = ?
   S₁t₁ = S₂t₂
   

   60 ×	210	= 80 × t2
   	60

   
   

   t2 = 2	5	hrs
   	8

   Correct Option: B

   Speed of train = 60 kmph
   Time = 210 minutes
   

   =	210	hours
   	60

   
   

   or	7	hours
   	2

   
   

   Distance covered = 60 ×	7	= 210 km
   	2

   
   

   Time taken at 80 kmph =	210	=	21	hours
   	80		8

   
   

   = 2	5	hours
   	8

   
   
   Second Method :
   

   Here, S1 60, t1 =	210	hrs
   	60

   
   S₂ = 80, t₂ = ?
   S₁t₁ = S₂t₂
   

   60 ×	210	= 80 × t2
   	60

   
   

   t2 = 2	5	hrs
   	8

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