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Can someone explain this for me step by step? Abby rows 10 km upstream and 10 km back in a total time of 3 hr. The speed of the river is 5 km/h. Find Abby’s speed in still water. @mark_o.
 one year ago
 one year ago
Can someone explain this for me step by step? Abby rows 10 km upstream and 10 km back in a total time of 3 hr. The speed of the river is 5 km/h. Find Abby’s speed in still water. @mark_o.
 one year ago
 one year ago

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mark_o.Best ResponseYou've already chosen the best response.1
yeah im here now lol :D dw:1354646559750:dw
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
she row from starting point A to B then from B to A that is time from A to B + time from B to A = 3 hours
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
time Tab + T ba = 3 (1) but distance d=velocity x time,. therefore t=d/v dAB dBA  +  =3 but distances dBA=dAB=10 km v v 10 10  +  =3 v v but note that velocity of river is v=5 km/hr for upstream v= v+5 10 10 for down stream v= v5, therefore  + = 3 v+5 v5 you can algebra now ion finding v=?
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
i mean you can do the algebra now from this point ... :D
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
10/(v+5) + 10 /(v5) =3 10(v5) + 10(v+5)  =3 (v+5)(V5)
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
do multiplication and addition to simplify the numerator and the denominator..:D
 one year ago

andjieBest ResponseYou've already chosen the best response.0
wow i suck cause I am lost
 one year ago

andjieBest ResponseYou've already chosen the best response.0
the v is throwing me off
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
10 10  +  = 3 (v+5) (v5) ?  =3 (v+5) (v5)
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
for the further left, that is (v+5)(v5) = ? then mult by 10 (v+5)
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
then on the mid of it (v+5)(v5) = ? then mult by 10 (v5)
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
10(v5) + 10(v+5  = 3 (v+5)(v5)
 one year ago

andjieBest ResponseYou've already chosen the best response.0
ok give me a sec and let me figure this out
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
multiply the numerator then do addition on the denominator multiply them also
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
hhm where did you get 105 and 15+5 from? it should stay as 10( v5)=? and 10(v+5)=?
 one year ago

andjieBest ResponseYou've already chosen the best response.0
I SUBTRACTED AND ADDED 10 FROM BOTH (V5)(V+5)
 one year ago

andjieBest ResponseYou've already chosen the best response.0
I just want to understand it
 one year ago

HeroBest ResponseYou've already chosen the best response.1
I guess you didn't like my explanation
 one year ago

andjieBest ResponseYou've already chosen the best response.0
no i asked you a question and you left
 one year ago

andjieBest ResponseYou've already chosen the best response.0
I just hate math and it takes me awhile to get it together
 one year ago

HeroBest ResponseYou've already chosen the best response.1
Well, I just answered your question
 one year ago

HeroBest ResponseYou've already chosen the best response.1
I left the room to help someone else with their question, but you should not assume that I had left.
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
it should stay as 10( v5)=? and 10(v+5)=? 10( v5)= 10v 50 is it ? and 10(v+5)= 10v +50 is it ?
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
ahh you have posted this before..yeah @andjie when we start coaching you dont assume that we had left .. :D
 one year ago

HeroBest ResponseYou've already chosen the best response.1
@mark_o. I am convinced you are doing this the hard way.
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
and for the denominator (v+5)(V5)=?
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
haha i know..:D im sorry @Hero ...:D
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
where is that? lol... :D
 one year ago

HeroBest ResponseYou've already chosen the best response.1
I'll do anything to avoid a quadratic equation
 one year ago

HeroBest ResponseYou've already chosen the best response.1
Besides, I don't like when you get to a result where you have two solutions but have to discard one of them because it is negative.
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
i think andjie is just doing the refresher thing now.. to recall everything .. that was 7 years ago ? @ andjie?
 one year ago

HeroBest ResponseYou've already chosen the best response.1
http://openstudy.com/study#/updates/50bd6019e4b0de42629fcb42
 one year ago

andjieBest ResponseYou've already chosen the best response.0
wait I just had my high school reunion so it was 10 years ago lol
 one year ago

HeroBest ResponseYou've already chosen the best response.1
She's probably 28 years old
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
wow, almost 10 years ago? hmmm yeah this is a good refresher to you ... :D
 one year ago

HeroBest ResponseYou've already chosen the best response.1
I just posted a link to the solution
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
hhhm i cant open it, dont know why @Hero
 one year ago

andjieBest ResponseYou've already chosen the best response.0
I understand this better @hero hopefully I can do more like this
 one year ago

HeroBest ResponseYou've already chosen the best response.1
d = rt and let r = b ± w b = speed of the boat w = speed of the water current t1 = Upstream time t2 = Downsteam time 10 = 5t 2 = t1 t1 + t2 = 3 2 + t2 = 3 t2 = 3  2 t2 = 1 Upstream Formula d = rt1 d = (b  w)t1 Downsteam Formula: d = rt2 d = (b + w)t2 b  w = 5 Upstream 10 = 2(b  w) Downsteam 10 = (b + w) 10 = 2b  2w 20 = 2b +2w 30 = 4b 30/4 = b 7.5 = b 10 = b + w 10 = 7.5 + w 10  7.5 = w 2.5 = w Therefore The speed of the boat was 7.5 km/h
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
ok this is good,, directly for the solutions and answer.... ;D
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
you did really avoid the quadratic equation .. :D
 one year ago

andjieBest ResponseYou've already chosen the best response.0
You guys are just too smart for me
 one year ago

HeroBest ResponseYou've already chosen the best response.1
I usually find ways to avoid it.
 one year ago

HeroBest ResponseYou've already chosen the best response.1
It's a personal goal of mine
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
ok that is very good.... and andjie can copy this one to study and do for a second solution or alternate solution..........:D
 one year ago

andjieBest ResponseYou've already chosen the best response.0
Thank you @mark_o. you always look out for me
 one year ago

HeroBest ResponseYou've already chosen the best response.1
Well, back to watching Smallville. I'm trying to get to the end of the 10th season and it's taking forever.
 one year ago

andjieBest ResponseYou've already chosen the best response.0
Have fun and thank you for your help
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
ok YW,, tc now and have fun solving..........:D
 one year ago

mark_o.Best ResponseYou've already chosen the best response.1
thanks for doing the alternative solution, that was a good one :D @Hero...............:D
 one year ago

HeroBest ResponseYou've already chosen the best response.1
You're welcome. I have plenty alternative solutions up my sleeve.
 one year ago

HeroBest ResponseYou've already chosen the best response.1
If you need an alternative solution, cite me.
 one year ago
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