Question

A boat goes 6 km in an hour in still water. it takes thrice as much time in covering the same distance against the current. speed of the current is?

Answer 1

Let the velocity of the boat be v km/h and velocity of the current be u km/h. 

When the boat goes in still water, its velocity is v=6 km/h. 

When the boat goes against the current, its velocity is v-u=(6-u) km/h. 

For distance S, time taken in still water to cover the distance = S/6 hous 

For same distance S, time taken while going against the current = S/(6-u) hours. 

According to given, S/(6-u) = 3*(S/6) 

=> 1/(6-u) = 1/2 
=> 6-u = 2 
=> u=4 km/h. 

So, the speed of the current is 4 km/h.
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