SOLUTION: Starting at home, Stephanie traveled uphill to the gift store for 30 minutes at just 10 mph. She then traveled back home along the same path downhill at a speed of 30 mph. What

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Question 697316: Starting at home, Stephanie traveled uphill to the gift store for 30 minutes at just 10 mph. She then traveled back home along the same path downhill at a speed of 30 mph.
What is her average speed for the entire trip from home to the gift store and back?

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Starting at home, Stephanie traveled uphill to the gift store for 30 minutes at just 10 mph. She then traveled back home along the same path downhill at a speed of 30 mph.
What is her average speed for the entire trip from home to the gift store and back?
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avg = 2*10*30/(10+30)
= 15 mi/hr regardless of distance
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The long way:
30 mins (1/2 hr) at 10 mi/hr --> d = 5 miles
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5 miles @ 30 mi/hr = 1/6 hour
Total time = 2/3 hour
Total distance = 10 miles
r = 10/(2/3) = 15 mi/hr