Boat and Stream Questions, short tricks | Stream and Boat tricks.

Boat and Stream Questions, short tricks :
Boat and Stream Questions
Important points :
1) If the boat is moving in the direction of the current, the two speeds should be added.
2) Subtract both speeds as the boat is moving in the opposite direction.

Important Formulas :
Suppose,
The speed of the boat towards the stream = a
The boat speeds in the opposite direction to the current = b
1 ) The speed of the boat in slow water = ( a + b ) / 2.
2 ) Flow Speed = ( a - b ) / 2.

Boat and Stream Questions :

1) 30 km / hr in the direction of a boat flow. It travels at a speed of 24 km / hr against the current. So speed up the slow water flow of the boat?
Ans. :
The speed of the boat in slow water = ( a + b ) / 2.
= ( 30 + 24 ) / 2
= 54 / 2.
= 27 km/hr.
 Flow Speed = ( a - b ) / 2.
= ( 30 - 24 ) / 2
= 6 / 2
= 3 km/hr.

2) 12 km / hr in the direction of a boat flow. It travels at a speed of 8 km / hr against the current. So speed up the slow water flow of the boat?
Ans :
The speed of the boat in slow water = ( a + b ) / 2.
= ( 12 + 8 ) / 2
= 20 / 2.
= 10 km/hr.
Flow Speed = ( a - b ) / 2.
= ( 12 - 8 ) / 2
= 4 / 2
= 2 km/hr.

3) If a person swims 42 km in the direction of the current and 30 km in the opposite direction of the current every 6 hours, then calculate the speed of the current.
Ans. :
The speed of man towards the stream = 42 / 6 = 7 km/hr.
Man's velocity in the opposite direction of flow = 30 / 6 = 5 km/hr.
Flow Speed = ( 7 - 5 ) / 2 = 2 / 2 = 1 km/hr.

4) A person swims in the direction of the stream at a speed of 15 km / hr. If the velocity of flow is 3 km / hr, So what is the speed of that person in the opposite direction of the current ?
Ans. :
Suppose a person speeds up against the current = x
The velocity of the person towards the stream = 15 km / hr.
Flow Speed = 3 km/hr.
Flow speed = ( velocity in the direction of flow ) - ( velocity in the opposite direction of flow )  / 2.
3 = ( 15 - x ) / 2
6 = 15 - x
x = 15 - 6
x = 9.

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