## Speed, Time and Distance

#### Speed, Time and Distance

1. 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 ?
1. 12 hrs. 36 min.
2. 16 hrs. 48 min.
3. 16 hrs. 4 min.
4. 15 hrs. 32 min.

1. Required time = (4 / 15) x 63 hrs.

##### Correct Option: B

Required time = (4 / 15) x 63 hrs.
= 16 hrs. 48 min

1. A train is moving with a speed of 92.4 km/hr. how many meters will it cover in 10 min. ?
1. 1540
2. 15400
3. 154
4. 15.4

1. 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

##### Correct 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.

1. if a man cover 10.2 km. in 3 hours. The distance covered by him in 5 hours is ?
1. 18 km.
2. 15 km.
3. 16 km.
4. 17 km.

1. 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

1. A man crosses a streets 600 m long in 5 minutes. His speed in km per hour is ?
1. 7.2
2. 3.6
3. 10
4. 8.4

1. 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.

1. 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 ?
1. 12.5 km/hr.
2. 10.25 km/hr.
3. 11.52 km/hr.
4. 12.32 km/hr.

1. 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