Question 482313
Donald and Eric swam as a team in a relay race.
 Donald swam at a steady 3 km/h while Eric returned at an average rate of 4 km/h.
 Their total time was posted as 5 h 15 min. How long did Eric swim?
:
Change 5 hrs 15 min to 5.25 hrs
:
Find the distance first
Let d = the one-way distance
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Write a time equation; time = dist/speed
:
D's time + E's time = 5 hr 15 min
{{{d/3}}} = {{{d/4}}} = 5.25 
multiply by 12 to clear the denominators
4d + 3d = 12(5.25)
7d = 63
d = 63/7
d = 9 km is the one way distance
:
Find Eric's time
t = 9/4
t = 2.25 hrs is E's swim time
:
:
Confirm the solution by finding the total time
9/4 = 2.25
9/3 = 3.00
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total 5.25 hrs