SOLUTION: Donald and Eric swam as a team in a relay race. Donald swam at a steady 3km/h while Eric returned at an average rate of 4km/h. Their total time was posted as 5 h 15 min. How long d

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Question 476007: Donald and Eric swam as a team in a relay race. Donald swam at a steady 3km/h while Eric returned at an average rate of 4km/h. Their total time was posted as 5 h 15 min. How long did Eric swim?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Donald and Eric swam as a team in a relay race.
Donald swam at a steady 3km/h while Eric returned at an average rate of 4km/h.
Their total time was posted as 5 h 15 min.
How long did Eric swim?
:
Change 5 hr 15 min to 5.25 hrs
:
Find the one-way distance
d = one way dist
:
Write a time equation; time = dist/speed
:
D's time + E's time = 5.25 hrs
d%2F3 + d%2F4 = 5.25
multiply by 12 to clear the denominators, results:
4d + 3d = 12(5.25)
7d = 63
d = 63%2F7
d = 9 km is the one-way dist
:
Find E's swim time
9%2F4 = 2.25 hrs or 2 hrs 15 min