SOLUTION: hi! im having some problems with my word problem. Ann regularly swam .4 km in 20 min at the school pool. Swimming in a river against the current, she swan .25 km in the same

Question 126677: hi!
im having some problems with my word problem.
Ann regularly swam .4 km in 20 min at the school pool. Swimming in a river against the current, she swan .25 km in the same time it took Ann to swim .75 km with the current. Dind the speed of the current and the time it took ann to swim.
help please!
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Ann regularly swam .4 km in 20 min at the school pool. Swimming in a river against the current, she swam .25 km in the same time it took Ann to swim .75 km with the current.
:
Find the speed of the current and the time it took Ann to swim.
:
Find her speed in km/h
.4 in 20 min = 3 * .4 = 1.2 km/hr
:
Let x = speed of the current in km/hr
:
Speed upstream = (1.2 - x}
Speed downstream = (1.2 + x)
:
Write a time equation: (Time = distance/speed
:
Upstream time = downstream time
=
Cross multiply and you have:
.25(1.2+x) = .75(1.2-x)
:
.3 + .25x = .9 - .75x
:
.25x + .75x = .9 - .3
:
1x = .6 km/hr is the current
;
:
Find the time she swam:
:
Speed upstream: 1.2-.6 = .6 km/hr
Speed downstream: 1.2+.6 = 1.8 km/hr
:
.25/.6 = .41667 * 60 = 25 min( converting hrs to min)
also
.75/1.8 = .41667 * 60 = 25 min also, confirming our solutions
:
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