Question

The speed of boat in still water is 30 km/hr and the speed of water current is 4km/hr. What is the speed of boat down stream?​

Answer 1

Answer:

Let x = speed of boat in still water

 

Speed downstream = x+5

Speed upstream = x-5

 

Distance = (Rate)(Time), so Time = Distance/Rate

 

Time upstream = Time downstream

 

So, 20/(x-5) = 30/(x+5)

 

Cross multiply to get 20(x+5) = 30(x-5)

 

                              20x+100 = 30x-150

 

                                      10x = 250

 

                                         x = 25 km/hr