Question

The current of a stream runs at 1km/hr. A motor boat goes 35km upstream and back again to the starting point in 12 hours. The speed of the motorboat in still water is-------km/hr.

Answer 1

Heya user!!!!!
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Gud mrng!!!!!
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Here's your solution :-

Let the speed of the boat in still water be x km/hr....

Speed of the current =1km/hr.....
Then,

Speed of the boat upstream =(x-1)km/h

Speed of the boat downstream =(x+2)kmph....

Now Since distance =35km....

Therefore,

Time taken to go upstream =35/(x-1)h

Time taken to go downstream =35/(x+1) h

Given that the total time taken to move upstream and downstream is 12hrs...

Now, formulating the equation, we get :-

(35/x-1)+(35/x+1)=12

=>35(x+1)+35(x-1)/x²-1=12

=>70x=12(x²-1)

=>12x²-70x-12=0

=>6x²-35x-6=0

=>6x²-36x+x-6=0

=>6x(x-6)+(x-6)=0

=>(x-6)(6x+1)=0

=>x=6,-1/6

Since speed can't b in negative.......

Therefore, The answer is 6kmph.....

Hope this helps.....

:-)

Answer 2

Answer:

6 kmph .i think you got the answer for this question