SOLUTION: Melanie drives into the city to buy some new shoes. With traffic she only averages 15mph. On the way home it's much clearer so she averaged 35mph. If the total travel time is 2 hou

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Melanie drives into the city to buy some new shoes. With traffic she only averages 15mph. On the way home it's much clearer so she averaged 35mph. If the total travel time is 2 hou      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 986341: Melanie drives into the city to buy some new shoes. With traffic she only averages 15mph. On the way home it's much clearer so she averaged 35mph. If the total travel time is 2 hours how long did it take her to get to the store?
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Melanie drives into the city to buy some new shoes. With traffic she only averages 15mph. On the way home it's much clearer so she averaged 35mph. If the total travel time is 2 hours how long did it take her to get to the store?
----------------------
Avg speed of a round trip is:
2*R1*R2/(R1 + R2)
---
Her avg speed is 2*15*35/(50) = 21 mi/hr
RT distance = 2*21 = 42 miles--> 21 miles each way
----------------
Time going = 21/15 = 7/3 hrs = 2 hr 20 minutes