SOLUTION: Please help me so this word problem. {{{ The current of a river is 4 miles per hour . A boat travels to a point 6 miles upstream and back in 2 hours. What i

Question 1195643: Please help me so this word problem.
Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

Note: Don't put your whole question inside the "{}" symbols; those symbols are supposed to contain only mathematical equations or expressions.

Let x be the speed of the boat in still water. Then x+4 is its speed downstream (with the current) and x-4 is its speed upstream (against the current).

Time to go upstream 6 miles: 6/(x-4)
Time to got downstream 6 miles: 6/(x+4)
The total time is 2 hours:

Multiply by the least common denominator, (x-4)(x+4):

or

Obviously the negative solution makes no sense, so x=8.

ANSWER: the speed of the boat in still water is 8mph.

CHECK:

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