The speed of a river current is 3 km/h . A boat takes the same time to travel 15km upstream as it does to travel 18 km downstream. Find the speed of the boat in still water .
Answers
In the above Question , the following information is given - .
The speed of a river current is 3 km/h .
A boat takes the same time to travel 15km upstream as it does to travel 18 km downstream.
To find -
Find the speed of the boat in still water .
Solution -
Let us assume that the required speed of the boat in still water is x kmph .
Now ,
The speed of a river current is 3 km/h .
So ,
When this boat travels downstream -
Net Speed Downstream -
=> ( x + 3 ) kmph
So ,
When this boat travels upstream -
Net Speed upstream -
=> ( x - 3 ) kmph
Now ,
Speed = [ Distance / Time ]
The boat takes the same time to travel 15km upstream.
Let the time taken to cover this distance be t hours .
( x - 3 ) = 15 / t ........ { 1 }
The boat takes the same time to travel 18km downstream.
( x + 3 ) = 18 / t .......... { 2 }
Now ,
Divide equation 1 by equation 2
=> [ x - 3 ][ x + 3 ] = [ 5 / 6 ]
=> 5 ( x + 3 ) = 6 ( x - 3 )
=> 5x + 15 = 6x - 18
=> x = 15 + 18
=> x = 33 kmph .
Hence , the required speed of the boat in still water is 33 kmph .
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☞ Speed of boat in still water is 33 km/h
✭ Speed of a river current is 3 km/h
✭ A goat takes the same time to travel 15 km upstream as it does to travel 18 km downstream
➠ Speed of boat in still water?
Let us assume the speed of boat in still water as x km/h
Now,
In Upstream the speed of the boat is given by,
➢ Speed of boat in upstream = x - 3
In Downstream the speed of the boat is given by,
➳ Speed of boat in downstream = x + 3
We know that,
❍ Now to travel upstream,
➠
Now travelled downstream,
➠
Div EQ(1) by EQ(2)
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