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View Full Version : Another Probability Riddle No One Will Answer Correctly.


Titusfied
2003-09-30, 09:53 PM
A train and a bus randomly arrive at a mutual station between 9:00 A.M. and 10:00 A.M. The train stays at the station for 10 minutes upon its arrival, and the bus stays at the station for "x" minutes upon its arrival. How long does the bus have to stay at the station for the probability of the train and bus meeting each other to equal exactly 50%?

Good luck. This gets a much higher difficulty level than that dumb Car and Goat one I previously posted. If any of you get it, I'll be very impressed. And guesses will not be accepted, you must show your work, or explain it at least.

Hint: The answer is actually a pretty in-depth one. The use of formulas and the knowledge of probability and critical thinking is next to required.

Mantralord
2003-09-30, 10:33 PM
You're obviously taking a probability class in college, and because of the fact that you enjoy it and do well in it (probably better than all your other classes), you think you're better than other people, and wish to prove it by posting these "probability riddles" which only assholes that have gone through your class can answer. As most assholes haven't gone through your class, most cannot answer it, and you get a false feeling of superiority.

Nonetheless, I will try writing a brute force program to answer this for me.

Titusfied
2003-09-30, 10:58 PM
Actually, yes, I am taking this class right now, which I've indicated in the previous riddle, and no, I don't get a sense of superiority out of this, I have enough trouble doing them myself... I've also indicated the necessary knowledge needed to complete these in this riddle as well.

I like seeing how people tend to attack problems that actually cause them to use their brain.

Mantralord
2003-09-30, 11:52 PM
Well, an hour later we've worked together and got it to around 26.8337 minutes. Hooray for teamwork!

Titusfied
2003-09-30, 11:56 PM
And if you notice, that time is the length of the hypotenuse "X" in the Trapezoid picture I posted with those givens written at the bottom.

That picture was how I solved the problem by hand. Mantra used a Brute Force program and confirmed this. If anyone can tell me why I used that picture and how I got to that point (How I got those particular values for the given information and what not), I swear I will send them $5 via paypal. :)

Eddie_Perez
2003-10-01, 05:35 AM
What if everyone started posting rediculusly hard/complicated questions from their college classes...

Titusfied
2003-10-01, 08:29 AM
Then I would be able to answer them.

Mantralord
2003-10-01, 09:07 AM
And I would be able to brute force them.

!King_Amazon!
2003-10-01, 10:00 AM
How about we stop talking about titus being in college and taking this class, and start trying to disect the answer.

Medieval Bob
2003-10-01, 10:36 AM
I only looked at one case (x = 30) which results in a 58 1/3% chance so I would assume Grav's answer is accurate. I would actually try to answer this, but I've got some physics to work on...

However, due to Titus's outbreak: Then I would be able to answer them.

I'll post a few of simpler problems from Chapter 37 Sections 4-6 and 8 (Simultaneity, Time Dilation and the Twin Paradox, Length Contraction, and Galilean and Lorentz Transformations, respectively) from my PHYS 1444 class.

1) A certain type of elementary particle travels at a speed of
2.70x10^8 m/s. At this speed, the average lifetime is measured to be 4.76x10^-6 s. What is the particle's lifetime at rest?

2) A certain star is 95.0 light-years away. How long would it take a spacecraft traveling .960c to reach that star from Earth, as measured by observers: (a) on Earth, (b) on the spacecraft? (c) What is the distance traveled according to observers on the spacecraft? (d) What will the spacecraft occupants compute their speed to be from the results of (b) and (c)?

3) A farm boy studying physics believes that he can fit a 13.0m long pole into a 10.0m long barn if he runs fast enough, carrying the pole. Can he do it? Explain in detail. How does this fit with the idea that when he is running the barn looks even shorter than 10.0m?

Mantralord
2003-10-01, 10:57 AM
I'll know how to do those when I go through "PHYS 1444" class myself.

LiveWire
2003-10-03, 12:44 AM
And I would be able to brute force them.
Dont know why but i laughed my ass off on that one lol

I see no answers :wierd:

Raziel
2003-10-03, 02:13 AM
Fuck math. Fuck it good, fuck it hard.

Eddie_Perez
2003-10-03, 08:42 AM
Fetish :x
------------------------

I have problems with math since I didn't lean crucial shit when I was younger which was needed to understand this shit and so on.... I'm just a mess... *tear*

!King_Amazon!
2003-10-03, 11:58 AM
No, it's because you're mexican.

LiveWire
2003-10-03, 12:39 PM
haha lol pwnED

Apoq
2003-10-03, 01:21 PM
my turn i ask question from my ap stats class.

33. Explain why this is not true.
Good teachers make bad researchers, and bad teachers make good researchers.

(context is correlation/causation)

Grav
2003-10-03, 02:26 PM
so I would assume Grav's answer is accurate.

Damn straight.