Speed of boat in still water

A

alwaysgame

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I am working on a problem where a boat travels from its dock and goes 5 miles up river in an undefined about of time. Because of the 4 mph current it took the boat 20 minutes less to go back down river to its dock. How fast will it go in still water?

I have set up several variations of D = Rate/Time but I cannot seem to get the right formula. I know going upstream it is x+4 and down it is x-4 but I am lost from there. Help please.
 
alwaysgame said:
I have set up several variations of D = Rate/Time …
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Hello alwaysgame:

Distance is not the ratio of rate to time; it's their product. (This might be one reason for your difficulties.)

D = R * T

You did not show your work, so I'm not sure what you did.

Are you writing a system of two equations?

Are you using x+4 and x-4 as the rates, in these two equations?

Do you realize that D has the same value, in each of these two equations?

If you need more help, then please show your work or explain what you're doing, so that we might determine where to continue helping you.

Cheers,

~ Mark

 


You might find the following discussion helpful, too. I found it by searching this site on keywords: in still water.

CLICK HERE

Hmmm, searching on keywords 'river current' brings up a few more examples. Try it!

 
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