In one hour Dan drives 25 miles farther in his car than Ron can cycle on his bike. If it takes Ron one and a half hours longer to cycle 75 miles than it takes Dan in his car, how fast can Ron cycle?
Not sure if this is right. I'm pretty sick and it's late.
R = D - 25
D = 1.5R
25 = 1.5R - R
25 = R(1.5 -1)
R = 25/.5
R = 50
Doesn't 50 mph on a bike seem a little umm... far fetched?
Quote from: Ergot on May 16, 2006, 02:56:45 AM
Doesn't 50 mph on a bike seem a little umm... far fetched?
On average, yeah, but it's definitely possible. I'm pretty sure I've done it before (downhill, but still).
I see my problem, though... hold on. Working on a intelligible answer.
Well I started with rt=D
So rD*t = (rR*t) + 25
t = 1 so I get rD = rR + 25
75 = rR(tD + 3/2)
rD*tD = 75
Subsititute this up there...
75 = rR(75/rD + 3/2)
Then we plug in rD that we found in the beginning...
75 = rR(75/(rR + 25) + 3/2)
Solving... 0 = 3rR2 + 225rR - 75
I'm not doing something right... so I tried r=t/d but then that just got me something stupid too x_x
False or 16 2/3 MPH
t = time, D = Dan's rate, R = Ron's rate
EQ 1. tD-tR=25 when t =1
EQ 2. tD = (t+1.5)R
sub EQ 2 in EQ 1
1.5R = 25
R = 50/3
According to my calculations... (they might be wrong...)
It'll take Ron 4.5 hours for 75 miles.
It'll take Dan 1.8 hours for 75 miles.
4.5 - 1.8 != 1.5 ? I'm not saying you're wrong... but the difference in their time doesn't work out for me... can you show me Dan's rate/time too ?
I get 37.5 MPH for Dan.
Quote from: Nate on May 16, 2006, 10:35:40 PM
I get 37.5 MPH for Dan.
Then 4.5 hours for Ron... 2 hours for Dan. That's still not a 1.5 hour difference :( ?
Does this have anything to do with iago and Quik?
Quote from: Sidoh on May 16, 2006, 03:09:45 AM
Quote from: Ergot on May 16, 2006, 02:56:45 AM
Doesn't 50 mph on a bike seem a little umm... far fetched?
On average, yeah, but it's definitely possible. I'm pretty sure I've done it before (downhill, but still).
I see my problem, though... hold on. Working on a intelligible answer.
Doubt it. My absolute highest speed (downhill, wind behind me, pedalling as hard as I could) was 58km/h, or 36mph.
Quote from: iago on May 17, 2006, 01:42:57 PM
Doubt it. My absolute highest speed (downhill, wind behind me, pedalling as hard as I could) was 58km/h, or 36mph.
Yeah, but you have a Canadian bike. Canadian bikes don't have nuclear fuel cells. Duh.
Quote from: Ergot on May 16, 2006, 03:38:25 AM
Well I started with rt=D
So rD*t = (rR*t) + 25
t = 1 so I get rD = rR + 25
75 = rR(tD + 3/2)
rD*tD = 75
Subsititute this up there...
75 = rR(75/rD + 3/2)
Then we plug in rD that we found in the beginning...
75 = rR(75/(rR + 25) + 3/2)
Solving... 0 = 3rR2 + 225rR - 75
I'm not doing something right... so I tried r=t/d but then that just got me something stupid too x_x
what is all this gibberish
Then i go with my original answer of False. Their speeds aren't constant.
Quote from: BigAznDaddy on May 17, 2006, 05:05:05 PM
Quote from: Ergot on May 16, 2006, 03:38:25 AM
Well I started with rt=D
So rD*t = (rR*t) + 25
t = 1 so I get rD = rR + 25
75 = rR(tD + 3/2)
rD*tD = 75
Subsititute this up there...
75 = rR(75/rD + 3/2)
Then we plug in rD that we found in the beginning...
75 = rR(75/(rR + 25) + 3/2)
Solving... 0 = 3rR2 + 225rR - 75
I'm not doing something right... so I tried r=t/d but then that just got me something stupid too x_x
what is all this gibberish
It's called math. You're making a pretty lousy first impression here -- reminds me of the classic quote, "It's better foor one to be silent and thought a fool than to open one's mouth and remove all doubt"
Ron is going 25mph?
Edit: If only this were in the homework board, I would've seen it earlier.
Yea, how'd you get it? (I still didn't get it :().
Quote from: iago on May 17, 2006, 10:30:46 PM
Quote from: BigAznDaddy on May 17, 2006, 05:05:05 PM
Quote from: Ergot on May 16, 2006, 03:38:25 AM
Well I started with rt=D
So rD*t = (rR*t) + 25
t = 1 so I get rD = rR + 25
75 = rR(tD + 3/2)
rD*tD = 75
Subsititute this up there...
75 = rR(75/rD + 3/2)
Then we plug in rD that we found in the beginning...
75 = rR(75/(rR + 25) + 3/2)
Solving... 0 = 3rR2 + 225rR - 75
I'm not doing something right... so I tried r=t/d but then that just got me something stupid too x_x
what is all this gibberish
It's called math. You're making a pretty lousy first impression here -- reminds me of the classic quote, "It's better foor one to be silent and thought a fool than to open one's mouth and remove all doubt"
This is probably my third or fourth post crushing him. /signed.
Here's a few tips since this is probably your first forum ever:
1. Don't post about stuff you don't know.
2. Don't post something like; "yeah", "no", or " no that's not right ( without an explanation why. )
3. Don't post stuff like " what is all this gibberish? "