SOLUTION: Sandy can swim 1 mile upstream in 20 minutes. She can swim the same distance downstream in 9 minutes. Find the speed of the current and of Sandy if both stay constant.
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Question 251327: Sandy can swim 1 mile upstream in 20 minutes. She can swim the same distance downstream in 9 minutes. Find the speed of the current and of Sandy if both stay constant. Answer by solver91311(24713) (Show Source):
Let represent her speed in still water and let represent the speed of the current.
Since we know that distance equals rate times time, 20 minutes is one-third of an hour, 9 minutes is 3/20ths of an hour, her speed relative to dry land upstream (against the current) must be , and the speed downstream must be , we can say the following things:
With respect to the upstream trip:
And with respect to the downstream trip:
A little arithmetic:
Now all you need to do is solve the linear system. The coordinates of the single ordered pair in the solution set are the answers you seek.
