<PRE><B>Question 1046151</B>
You drive at an average of 30 miles per hour on the way to work, and at an average of 35 miles per hour on the way home. The total driving time is 30 minutes. How far away is work? Round your answer to the nearest hundredth of a mile.
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Avg speed of the round-trip is
2*30*35/(30+35) = 2100/65 mi/hr = 420/13 mi/hr
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RT distance = (420/13)*0.5 = 210/13 miles.
Each way = 105/13 = 8.08 miles
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The formula for avg speed of a RT (or 2 legs of equal length) is similar to parallel resistances or parallel work.
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