The speed of the current in a river is 6 mph. A ferry operator who works that part of the river is looking to buy a new boat for his business. Every day, his route takes him 22.5 miles each way against the current and back to his dock, and he needs to make this trip in a total of 9 hours. He has a boat in mind, but he can only test it on a lake where there is no current. How fast must the boat go on the lake in order for it to serve the ferry operator’s needs?

Question

The speed of the current in a river is 6 mph.  A ferry operator who works that part of the river is looking to buy a new boat for his business. Every day, his route takes him 22.5 miles each way against the current and back to his dock, and he needs to make this trip in a total of 9 hours. He has a boat in mind, but he can only test it on a lake where there is no current. How fast must the boat go on the lake in order for it to serve the ferry operator’s needs?

pooja195 · Answer

let x be the speed of boat
Every day, his route takes him 22.5 miles against the current and back to his dock, and he needs to make this trip in a total of 9 hours
=> 22.5/(x+6) + 22.5/(x-6) = 9
solving
x = 9 mph

anonymous · Answer

how did you get 6?

pooja195 · Answer

6mph

anonymous · Answer

ok, I get it, thank you...I'll give you best response ☺

pooja195 · Answer

http://openstudy.com/study#/updates/510045c6e4b00c5a3be6aace see if this helps

pooja195 · Answer

np