The speed of a stream is 4 mph. A boat travels 6 miles upstream in the same time it takes to travel 14 miles downstream. What is the speed of the boat in still water?

1 Answer
Shwetank Mauria
May 31, 2016

The speed of boat in still water be 10 mph.

Explanation:

Let the speed of boat in still water be x mph. AS, the speed of stream is 4 mph, upstream speed will be (x-4) and downstream speed will be (x+4).

Time taken by boat for travelling 6 miles upstream will be 6/(x-4) and time taken by boat for travelling 14 miles downstream is 14/(x+4).

As the two are equal

6/(x-4)=14/(x+4) or 6(x+4)=14(x-4) or

6x+24=14x-56

Hence 14x-6x=24+56=80 or 8x=80.

Hence x=10.

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