document.write( "Question 252959: A hiker can walk at an average speed of 2 mph uphill and 6 mph downhill. Suppose he takes a hike on a mountain road which goes only uphill or downhill. What will be his average speed for such a trip, assuming he finishes at the level he started? \n" ); document.write( "

Algebra.Com's Answer #185149 by drk(1908) $\"\"$ $\"About$

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We have to set up a RTD chart
\n" ); document.write( "hiker . . . . .rate . . . . .time . . . . . .distance
\n" ); document.write( "up . . . . . . .2 . . . . . . . d/2 . . . . . . . d
\n" ); document.write( "down . . . . .6 . . . . . . . d/6 . . . . . . . d
\n" ); document.write( "I assume he walks the same trail up and down, so that is the same distance.
\n" ); document.write( "time is distance / rate, so we have our 2 times.
\n" ); document.write( "we want average rate (speed). This is total distance over total time.
\n" ); document.write( " $\"2d+%2F+%28d%2F2+%2B+d%2F6%29\"$
\n" ); document.write( "adding the fractions, we get
\n" ); document.write( " $\"2d+%2F+%284d%2F6%29\"$
\n" ); document.write( "multiply by reciprocal, we get
\n" ); document.write( " $\"12d%2F4d\"$
\n" ); document.write( "His average rate is 3 mph \n" ); document.write( "

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