# A boat goes 9 km an hour in still water. But it takes thrice as much time in going the s ame distance against the current. What is the speed of the current?

Lets assume  the velocity of the boat be X km/h and velocity of the current be y km/h.

It goes x=9 km/h in still water.
then when the boat goes against the current, its velocity is (x-y)=(9-y)km/h

For distance s, time taken in still water to cover the distance = S/9 seconds.
For same distance s, time taken while going against the current = S/(9-y) seconds

so the equation will be, S/(9-y) = 3 X (S/9)
=>1/(9-y)=1/3
=>9-y=3
=>y=6

So, the speed of the current is 6 km/h.

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