Question 948293: Starting at home, Ishaan traveled uphill to the grocery store for 8 minutes at just 30 mph. He then traveled back home along the same path downhill at a speed of 60 mph.
What is his average speed for the entire trip from home to the grocery store and back
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! Starting at home, Ishaan traveled uphill to the grocery store for 8 minutes at just 30 mph. He then traveled back home along the same path downhill at a speed of 60 mph.
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avg speed of the round trip = 2*30*60/(30+60) = 3600/90
= 40 mi/hr
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It's not reasonable to try to remember a formula for everything, but avg speed of a round trip is similar to parallel flows, parallel work, parallel resistors, etc.
Only the factor of 2 is different.
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