SOLUTION: A boy can row a boat at a constant rate of 5 mi/hr in still water, as indicated in the figure. He rows upstream for 23 minutes and then rows downstream, returning to his starting p

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: A boy can row a boat at a constant rate of 5 mi/hr in still water, as indicated in the figure. He rows upstream for 23 minutes and then rows downstream, returning to his starting p      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 838880: A boy can row a boat at a constant rate of 5 mi/hr in still water, as indicated in the figure. He rows upstream for 23 minutes and then rows downstream, returning to his starting point in another 17 minutes.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
It looks like you want the speed of the current
Let +c+ = the speed of the current and
the distance he rows
-----------------------
Rowing downstream:
(1) +d+=+%28+5+%2B+c+%29%2A%28+17%2F60+%29+
Rowing upstream:
(2) +d+=+%28+5+-+c+%29%2A%28+23%2F60+%29+
----------------------------
Substitute (1) into (2)
++%28+5+%2B+c+%29%2A%28+17%2F60+%29+=+%28+5+-+c+%29%2A%28+23%2F60+%29+
Multiply both sides by +60+
++%28+5+%2B+c+%29%2A17+=+%28+5+-+c+%29%2A23+
+85+%2B+17c+=+115+-+23c+
+40c+=+30+
+c+=+3%2F4+
The speed of the current is 3/4 mi/hr
check:
(1) +d+=+%28+5+%2B+.75+%29%2A%28+17%2F60+%29+%0D%0A%281%29+%7B%7B%7B+d+=+5.75%2A.28333+
(1) +d+=+1.629+
and
(2) +d+=+%28+5+-+.75+%29%2A%28+23%2F60+%29+
(2) +d+=+4.25%2A.38333+
(2) +d+=+1.629+
The one-way distance he rows is 1.629 mi