SOLUTION: A boat's crew rowed 7.5miles downstream, with the current, in 1.5hours. The return trip upstream, against the current, covered the same distance, but took 2.5 hours. Find the cre

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Question 384465: A boat's crew rowed 7.5miles downstream, with the current, in 1.5hours. The return trip upstream, against the current, covered the same distance, but took 2.5 hours. Find the crew's rowing rate in still water and the rate of the currnet.
The crew's rowing rate in still water is _____ mile(s) per hour.
The rate of the current is ____ mile(s) per hour.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi,   

D = r*t      

Let (x+c) and (x-c) represent speed downstream and upstream respectively

Question states

 7.5mi = 1.5hrs(x+c) solving for x

 7.5/1.5 - c = x

     5 -c = x



7.5(x-c) = 2.5hr  

    (x-c) = 2.5/7.5   substituting for x to solve for c

    [(5-c) - c] = 1/3

        5 - 2c = 1/3

        15/3 - 1/3 = 2c

         14/3 = 2c

           c = 7/3 or 2 1/3mph  the speed of the current

           x = 2 2/3mph  the speed of the boat in still water

CHECKING our Answer

  3/2hr * 5mph = 15/2 = 7.5mi