SOLUTION: Sigh! I just don't get this stuff : ( Very frustrating. Please help. A boat can maintain a speed of 16mph. The boat makes a trip upstream in 20 mins. The return trip takes 15

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Question 223211: Sigh! I just don't get this stuff : ( Very frustrating. Please help.
A boat can maintain a speed of 16mph. The boat makes a trip upstream in 20 mins. The return trip takes 15 minutes. What is the speed of the current?
Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
A boat can maintain a speed of 16mph.
The boat makes a trip upstream in 20 mins.
The return trip takes 15 minutes. What is the speed of the current?
:
Change min to hrs:
15 min = 15/60 = 1/4 hr
20 min = 20/60 = 1/3 hr
:
Let c = speed of the current
then we can say:
(16 - c) = boat speed up stream
and
(16 + c) = boat speed down stream
:
The distance up and the distance back are equal. Write a distance equation
Dist = time * speed
;
Up dist = down dist
(16-c) = (16+c)
Multiply both sides by 12 to get rid of those denominators
4(16-c) = 3(16+c)
64 - 4c = 48 + 3c
64 - 48 = 3c + 4c
16 = 7c
c =
c = 2.2587 mph speed of the current
:
:
We can confirm this solution by finding the distance of each, should be equal
.25(16 + 2.2587) = 4.57 miles
.33(16 - 2.2587) = 4.57 miles