151. Express speed of 60 metres per sec. in km per hour.

1. 1. 232 kmph

   
   
   

   2. 216 kmph

   
   
   

   3. 116 kmph

   
   
   

   4. 118 kmph

   
   
   

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1. View Hint View Answer Discuss in Forum

   60 metres per sec.
   

   =		60 ×	18		km per hr.
   			5

   
   = 216 km per hr.

   Correct Option: B

   60 metres per sec.
   

   =		60 ×	18		km per hr.
   			5

   
   = 216 km per hr.

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152. A man covers 20 kms in 2 hours.

     Find the distance covered by him in 5	1	hours.
     	2

1. 1. 50 km

   
   
   

   2. 65 km

   
   
   

   3. 55 km

   
   
   

   4. 45 km

   
   
   

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1. View Hint View Answer Discuss in Forum

   Distance = 20 kms
   Time = 2 hours
   

   ∴  Speed =	Distance
   	Time

   
   

   =	20	= 10 km per hr.
   	2

   
   Now, we have, Speed = 10 km per hr.
   

   Time =	11	hr.
   	2

   
   ∴  Distance = Speed × Time
   

   = 10 ×	11	= 55 km
   	2

   Correct Option: C

   Distance = 20 kms
   Time = 2 hours
   

   ∴  Speed =	Distance
   	Time

   
   

   =	20	= 10 km per hr.
   	2

   
   Now, we have, Speed = 10 km per hr.
   

   Time =	11	hr.
   	2

   
   ∴  Distance = Speed × Time
   

   = 10 ×	11	= 55 km
   	2

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153. A car runs at 60 km per hr. A man runs at one-third the speed of the car and reaches office from his house in 15 minutes. How far is his office from his house?

1. 1. 7 km

   
   
   

   2. 5.5 km

   
   
   

   3. 6 km

   
   
   

   4. 5 km

   
   
   

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1. View Hint View Answer Discuss in Forum

   Man’s speed =	1	of the speed of car
   	3

   =	1	× 60 = 20 km per hr.
   	3

   
   Time taken to reach office= 15
   

   minutes =	15	=	1	hr.
   	60		4

   
   ∴  Distance between his house and office
   = Speed × Time
   

   = 20 ×	1	= 5 km.
   	4

   Correct Option: D

   Man’s speed =	1	of the speed of car
   	3

   =	1	× 60 = 20 km per hr.
   	3

   
   Time taken to reach office= 15
   

   minutes =	15	=	1	hr.
   	60		4

   
   ∴  Distance between his house and office
   = Speed × Time
   

   = 20 ×	1	= 5 km.
   	4

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154. Walking at a speed of 6 km per hour, a man takes 5 hours to complete his journey. How much time will he need to complete the same journey at the rate of 8 km per hr.?

1. 1. 3	3	hours
      	4

   
   
   

   2. 3 hours

   
   
   

   3. 2	3	hours
      	4

   
   
   

   4. 3.5 hours

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed = 6 km/hr
   Time taken = 5 hours
   ∴  Distance covered
   = 6 × 5 = 30 kms
   ∴  Time required to cover 30 kms
   at the speed of 8 km/hr.
   

   =	Distance	=	30	=	15	hours
   	Speed		8		4

   
   

   = 3	3	hours
   	4

   Correct Option: A

   Speed = 6 km/hr
   Time taken = 5 hours
   ∴  Distance covered
   = 6 × 5 = 30 kms
   ∴  Time required to cover 30 kms
   at the speed of 8 km/hr.
   

   =	Distance	=	30	=	15	hours
   	Speed		8		4

   
   

   = 3	3	hours
   	4

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155. A person covers 10 kms at 4 km per hr. and then further 21 kms at 6 km per hr. Find his average speed for whole journey.

1. 1. 5	1	kmph
      	3

   
   
   

   2. 5	1	kmph
      	6

   
   
   

   3. 5	1	kmph
      	2

   
   
   

   4. 4	1	kmph
      	2

   
   
   

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1. View Hint View Answer Discuss in Forum

   Case I.
   Distance = 10 kms
   Speed = 4 km/hr.
   

   ∴  Time taken (t2) =	21	=	7	hrs.
   	6		2

   
   

   Total time taken =	5	+	7
   	2		2

   
   

   =	5 + 7	= 6 hrs.
   	2

   
   Total distance covered
   = 10 + 21 = 31 kms
   

   ∴   Average Speed =	Total distance
   	Total time

   
   

   =	31	km per hr.
   	6

   
   

   = 5	1	km per hr.
   	6

   Correct Option: B

   Case I.
   Distance = 10 kms
   Speed = 4 km/hr.
   

   ∴  Time taken (t2) =	21	=	7	hrs.
   	6		2

   
   

   Total time taken =	5	+	7
   	2		2

   
   

   =	5 + 7	= 6 hrs.
   	2

   
   Total distance covered
   = 10 + 21 = 31 kms
   

   ∴   Average Speed =	Total distance
   	Total time

   
   

   =	31	km per hr.
   	6

   
   

   = 5	1	km per hr.
   	6

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