a motor boat can maintain a constant speed of 12mph relative to the water. The boat makes a trip upstream to a marina in 42 minutes. The return trip takes 1 hour and 45 minutes. What is the speed of the current? Hint Write system of equations. PLease help, i dont even know where to start.... :x
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word problem
- Thread starter Kdubb316
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Start:Kdubb316 said:a motor boat can maintain a constant speed of 12mph relative to the water. The boat makes a trip upstream to a marina in 42 minutes. The return trip takes 1 hour and 45 minutes. What is the speed of the current? Hint Write system of equations. PLease help, i dont even know where to start.... :x
Assume the speed of the current = x
So
speed upstream = 12 - x
speed downdtrem = 12 + x
and use
distance = speed * time
Now continue...
I think the times are backwards. It takes longer with the current than against it.
The distance is the same up and back.
Let x= rate of current.
Use d=rt
It takes 7/10 hours(42 minutes) to travel with the current:
\(\displaystyle \L\\\underbrace{\frac{7}{10}}_{\text{time}}\overbrace{(12+x)}^{\text{rate}}\)
It takes 7/4 hours against the current:
\(\displaystyle \L\\\frac{7}{4}(12-x)\)
Set them equal and solve for x.
The distance is the same up and back.
Let x= rate of current.
Use d=rt
It takes 7/10 hours(42 minutes) to travel with the current:
\(\displaystyle \L\\\underbrace{\frac{7}{10}}_{\text{time}}\overbrace{(12+x)}^{\text{rate}}\)
It takes 7/4 hours against the current:
\(\displaystyle \L\\\frac{7}{4}(12-x)\)
Set them equal and solve for x.