Question

a motor boat going downstream in a river covers the distance

between m and n in 4 hour traveling upstream it covers the same distance in 5 hours .if the speed of the stream is 3 km per hour find the speed of the streamer in still water ​

Answer 1

Step-by-step explanation:

Since we have to find the speed of the boat in still water, let us suppose that it is x km/h.

This means that while going downstream the speed of the boat will be (x+2) kmph because the water current is pushing the boat at 2 kmph in addition to its own speed 'x' kmph.

Now the speed of the boat down stream =(x+2) kmph

⇒ distance covered in 1 hour =x+2 km

∴ distance covered in 5 hours =5(x+2) km

Hence the distance between A and B is 5(x+2)km

But while going upstream the boat has to work against the water current.

Therefore its speed upstream will be (x−2) kmph.

⇒ Distance covered in 1 hour =(x−2) km

Distance covered in 6 hours =6(x−2) km

∴ distance between A and B is 6(x−2) km

But the distance between A and B is fixed

∴ 5(x+2)=6(x−2)

⇒ 5x+10=−12−10

∴ −x=−22

x=22

Therefore speed of the boat in still water is 22 kmph.

I hope help you