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anonymous
 5 years ago
A boat can go 25 mph in still water. It takes as long to go 160 miles upstream as it does to go downstream 240 miles. How fast is the current?
anonymous
 5 years ago
A boat can go 25 mph in still water. It takes as long to go 160 miles upstream as it does to go downstream 240 miles. How fast is the current?

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anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0\[T= \frac{D}{R}=\frac{160}{25+x}=\frac{240}{25x}\]

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0if x = current than rate going up stream is 25x and rate going down stream is 25+x

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0since \[T=\frac{D}{R} \] and these times are the same set them equal. then solve as a ratio \[160(25x)=240(25+x)\]

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0divide both sides by 80 to make life easier \[2(25x)=3(25+x)\] \[202x=75+3x\] \[5x=50\] \[x=10\] so i probably messed up and x = 10

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0oh yes of course. it is \[\frac{160}{25x}=\frac{240}{25+x}\] i had it backwards sorry

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0smaller distance over slower rate = bigger distance over bigger rate. my mistake. lets solve this one

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0\[160(25+x)=240(25x)\] \[2(25+x)=3(25x)\] \[20+2x=753x\] \[5x=50\] \[x=10\]

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0now we check. if the current is 10 mpr then the rate going up stream is 2510=15mph . \[\frac{160}{15}=10\tfrac{2}{3}\] hours

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0yea i screwed up twice. must be early

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0\[2(25+x)=3(25x)\] \[50+2x=753x\] \[5x=25\] \[x=5\]

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0can you do one more for me?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0whew. \[\frac{160}{20}=\frac{240}{30}=8\] so trip is 8 hours in either case

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0I just need a formula

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0yeah since clearly i am unable to solve a linear equation

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0A boat can go 150 miles downstream in the same time it can go 100 miles upstream. The speed of the current is 6 miles per hour.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Find the speed of the boat in still water.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0same exact eqution as before, only this time the variable will be speed, not current

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0again \[T=\frac{D}{R}\]

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0if you put x = speed of the boat then you know that the speed going downstream is x + 6 whereas the speed going up is x  6

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0so time going down is \[T=\frac{150}{x+6}\] and time going up is \[T=\frac{100}{x6}\]

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0set them equal and solve. \[\frac{160}{x+6}=\frac{100}{x6}\]

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0you can do this better than i can

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0typo \[\frac{150}{x+6}=\frac{100}{x6}\]
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