Question 1017606
Jane rides her bike to Lake Moultrie. Going to the lake she averages 12mph. On the return trip, she averages 10 mph. If the round trip takes a total of 5.5 hours, how long does the return trip take? 
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Avg speed of the round trip = 2*12*10/(10+12) = 120/11 mi/hr
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d = r*t = (120/11)*5.5 = 60 miles RT, 30 miles each way.
t = d/r = 30/10 = 3 hours returning