SOLUTION: A girl runs to the park to get her bicycle. Then she rides the bicycle back home. The total time for the round-trip is 45 minutes. Her running speed is 8 kph and her riding speed i

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Question 1116802: A girl runs to the park to get her bicycle. Then she rides the bicycle back home. The total time for the round-trip is 45 minutes. Her running speed is 8 kph and her riding speed is 24 kph. How far is the park from her home?
Answer by ikleyn(52795) About Me  (Show Source):
You can put this solution on YOUR website!
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Let L be the one way distance.


Then you have this "time" equation to find L:

L%2F8 + L%2F24 = 3%2F4   of an hour.      (!)


It is "time" equation, because each fraction in the left side is the time to cover the distance L at the corresponding speed.


From equation (1), after multiplying its both sides by 24, you have


3L + L = 3*6,   or

4L = 18  ====>  L = 18%2F4 = 9%2F2 = 41%2F2 = 4.5 km.


Check.  %28%289%2F2%29%29%2F8 + %28%289%2F2%29%29%2F24 = 9%2F16 + 9%2F48 = 27%2F48 + 9%2F48 = 36%2F48 = 3%2F4 of an hour.   ! Correct !

Solved.