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?
:
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/3}}} + {{{d/4}}} = 5.25
multiply by 12 to clear the denominators, results:
4d + 3d = 12(5.25)
7d = 63
d = {{{63/7}}}
d = 9 km is the one-way dist
:
Find E's swim time
{{{9/4}}} = 2.25 hrs or 2 hrs 15 min