Speed, Time and Distance
 If a man takes 4 hours to cover a distance of 15 km. how much time will be needed to cover 63 km. at the same speed ?

 12 hrs. 36 min.
 16 hrs. 48 min.
 16 hrs. 4 min.
 15 hrs. 32 min.

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Required time = (4 / 15) x 63 hrs.
Correct Option: B
Required time = (4 / 15) x 63 hrs.
= 16 hrs. 48 min
 A train is moving with a speed of 92.4 km/hr. how many meters will it cover in 10 min. ?

 1540
 15400
 154
 15.4

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Speed in m/sec = ( 5 / 18 ) x Speed in kms/hr.
92.4 kms/hr = 92.4 x (5 / 18) m/sec.
∴ Req. distance = 92.4 x ( 5 / 18 ) x 600 metersCorrect Option: B
Speed in m/sec = ( 5 / 18 ) x Speed in kms/hr.
92.4 kms/hr = 92.4 x (5 / 18) m/sec.
∴ Req. distance = 92.4 x ( 5 / 18 ) x 600 meters
= 15400 m.
 if a man cover 10.2 km. in 3 hours. The distance covered by him in 5 hours is ?

 18 km.
 15 km.
 16 km.
 17 km.

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Speed = 10.2 / 3 km/hr.
= 3.4 km/hr.
Distance covered in 5 hours = 3.4 X 5 km.Correct Option: D
Speed = 10.2 / 3 km/hr.
= 3.4 km/hr.
Distance covered in 5 hours = 3.4 X 5 km.
= 17 km
 A man crosses a streets 600 m long in 5 minutes. His speed in km per hour is ?

 7.2
 3.6
 10
 8.4

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Speed = 600 / (5 x 60) m/sec.
Correct Option: A
Speed = 600 / (5 x 60) m/sec.
= 600 / (5 x 60) x 18/5 km/hr.
= 7.2 km/hr.
 A and B are two towns. Mr. Faruqui covers the distance from A to B on cycle at 16 km/hr. however, he cover the distance from B to A on foot at 9 km/hr. his average speed during the whole journey is ?

 12.5 km/hr.
 10.25 km/hr.
 11.52 km/hr.
 12.32 km/hr.

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Average Speed = Total distance / time
= 2d / [( d / 16) + ( d / 9)]Correct Option: C
Average Speed = Total distance / time
= 2d / [( d / 16) + ( d / 9)]
= ( 2 x 16 x 9 ) / ( 16 + 9 ).
= 11.52 km/hr.
Shortcut :
Average speed = 2uv / (u + v)
= ( 2 x 16 x 9 ) / ( 16 + 9 )
= 11.52