Average SpeedDate: 08/26/97 at 20:50:32 From: Patapol Pawananon Subject: Algebra A person travels up a hill at 10 mph. and back down at 20 mph. What is the average speed for the entire trip? Date: 08/27/97 at 08:02:34 From: Doctor Anthony Subject: Re: Algebra The answer is NOT 15 mph because he spends longer at the slower speed. Let x = distance up the hill Time up the hill = x/10 Time down the hill = x/20 Total time = x/10 + x/20 = 3x/20 Total distance = 2x Average speed = 2x/(3x/20) = 40/3 = 13.333 mph -Doctor Anthony, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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