Speed, Time and Distance
 A train is running with the speed of 45 km/hour. What is its speed in meter per second ?

 12.5
 13.5
 20.5
 None of these

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Speed of a train in kilometer per hour = 45
Speed in meter per second = ( 5/18 ) x Speed in kilometer per hour
Correct Option: A
speed of a train in kilometer per hour =45
Speed in meter per second = ( 5/18 ) x Speed in kilometer per hour
= 45 x 5/18
= 12.5 kmph
 If a motor car covers a distance of 250 m in 25 second, What is its speed in kilometer per hour ?

 36.5
 36.8
 37
 36

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Speed of the motor car in meter per second = 250 / 25
= 10 m/s
Speed in km/hr = (18/5) x speed in m/sCorrect Option: D
Speed of the motor car in meter per second = 250 / 25
= 10 m/s
Speed in km/hr = (18/5) x speed in m/s
= 10 x (18 / 5) km/hour
=36 km/hour.
 A man takes 4 h 20 min in walking to a certain place and riding back. If he walk on both sides he losses 1 h. The time he would take by riding both ways is ?

 2 h 20 min
 3 h 20 min
 2 h
 4 h 40 min

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W + R = 4 h 20 min
W + W = 5 h 20 minCorrect Option: B
W + R = 4 h 20 min
W + W = 5 h 20 min
∴ R + R = 3 h 20 min
 A boat moves downstream at 1 km in 5 minutes and upstream at 1 km in 12 minutes.What is the speed of current?

 4.5 km/h
 3.5 km/h
 2 km/h
 2.5 km/h

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S_{d} = 12 km/h
S_{u} = 5 km/h
Speed of current = (S_{d}  S_{u})/2Correct Option: B
S_{d} = 12 km/h
S_{u} = 5 km/h
Speed of current = (12  5)/2 = 3.5 km/h
 A person goes to his office from his home at the speed of 4 km/h and return back at the speed of 6 km/h. Find the average speed of the person ?

 4.5 km/h
 5 km/h
 10 km/h
 4.8 km/h

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Average speed = 2ab/(a+b)
= (2 x 4 x 6)/(4 + 6)Correct Option: D
Average speed = 2ab/(a+b)
= (2 x 4 x 6)/(4 + 6)
= 48/10
= 4.8 km/h