Search found 540 matches

by Cradarc
Sat Feb 06, 2016 2:57 am UTC
Forum: Logic Puzzles
Topic: Six roll dice game
Replies: 11
Views: 3623

Re: Six roll dice game

I think Jeff's answer makes sense. The rolls are independent so it doesn't matter if you rolled 0 times or 5 times before. The fact of the matter is you have a total of six trials to get a desirable value. The probability of there being at least one 6 is: P 6 = 1-(5/6)^6 = ~0.6651 The pr...
by Cradarc
Fri Feb 05, 2016 10:26 am UTC
Forum: Mathematics
Topic: Infinite balls
Replies: 6
Views: 2549

Re: Infinite balls

I don't think it's a paradox. Fact 1: The number of balls in the room grows without bound with successive steps. Fact 2: Every ball placed in the room during any given step will be taken out in another future step. These two facts do not contradict because the number of steps are NOT finite. If you'...
by Cradarc
Fri Feb 05, 2016 10:05 am UTC
Forum: Logic Puzzles
Topic: Six roll dice game
Replies: 11
Views: 3623

Re: Six roll dice game

In the case of infinite games, just quit the instant you roll a profit and pay the lowest entry fee you can. Even the most optimal strategy will have the possibility of losing the bird in hand. Only gamble to avoid a loss.
by Cradarc
Fri Feb 05, 2016 12:08 am UTC
Forum: Logic Puzzles
Topic: Six roll dice game
Replies: 11
Views: 3623

Re: Six roll dice game

Suppose you rolled the value n on your kth roll. The probability you will roll something better if you continue is: 1-(n/6) 6-k In theory, if that probability is greater than 0.5, it would be advantageous to continue. However, because the sample size is small, you might opt for a higher thr...
by Cradarc
Sat Jan 30, 2016 11:01 pm UTC
Forum: Mathematics
Topic: How many pencils and how many jars I have?
Replies: 7
Views: 3206

Re: How many pencils and how many jars I have?

Guys this is actually a rather complicated problem. First of all, notice that after putting 9 pencils in each jar, he still has 2 jars left over. If leftover jars are the ones that do not contain pencils, where did the 18 pencils in those two jars go? Clearly there is a one-way worm hole in each of ...
by Cradarc
Fri Jan 22, 2016 7:21 pm UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13262

Re: Landing rockets upright is unnecessary?

Wow, that's mind-blowing. From the sound of things, most rocket boosters are no more durable than a homemade soda bottle rocket. The success rate of rocket launches is remarkable.
by Cradarc
Fri Jan 22, 2016 12:59 am UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13262

Re: Landing rockets upright is unnecessary?

Notice that the rocket did land vertically, and only the impact of tipping slightly was enough to explode. Yes, because hard concrete. There was no preparation made for the tip, so if the rocket fails to stay upright it's screwed. Have the rocket fall into a semi-elastic tarp which gives way at som...
by Cradarc
Thu Jan 21, 2016 11:02 pm UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13262

Re: Landing rockets upright is unnecessary?

How would you propose getting the rocket body to the ground in a horizontal orientation when your engine's thrust vector is pointed along the rocket body's axis? You don't purposefully rotate it. You simply focus on reducing its acceleration and if it ends up not upright, oh well. Attach parachutes...
by Cradarc
Thu Jan 21, 2016 8:40 pm UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 13262

Landing rockets upright is unnecessary?

First of all, I'm no rocket scientist, so I apologize for any ignorance I express. Lately, there's been a lot of news about relaunchable rockets, and this got me thinking. The problem of landing a rocket upright is ridiculously difficult. This is due to the fact that rockets have long, cylindrical s...
by Cradarc
Sat Jan 16, 2016 7:38 pm UTC
Forum: Logic Puzzles
Topic: Defective Circuit Board Puzzle
Replies: 7
Views: 3011

Re: Defective Circuit Board Puzzle

Wow, I must have been braindead when I made my first post. There obviously is a deterministic algorithm because the machine always identifies a faulty board if it is the only one in the set. I think Jestingrabbit has the optimal solution.
by Cradarc
Sat Jan 16, 2016 5:42 am UTC
Forum: Logic Puzzles
Topic: Defective Circuit Board Puzzle
Replies: 7
Views: 3011

Re: Defective Circuit Board Puzzle

How long does the machine take to run? The random nature can be exploited by leaving the same set of boards in the machine and running it multiple times. If the distribution is uniform you can be pretty confident there are no defective boards in that set. Any other distribution would allow you to id...
by Cradarc
Sat Jan 16, 2016 1:02 am UTC
Forum: The Help Desk
Topic: Wifi mysteriously broadcasting while disabled
Replies: 6
Views: 4083

Re: Wifi mysteriously broadcasting while disabled

Fixed! Thanks for the help!
by Cradarc
Thu Jan 14, 2016 11:49 pm UTC
Forum: The Help Desk
Topic: Wifi mysteriously broadcasting while disabled
Replies: 6
Views: 4083

Re: Wifi mysteriously broadcasting while disabled

Oh interesting. So basically the computer is telling the router to look for the printer which is turned off.
Is there a way I can make it stop these requests? Perhaps an option to turn off multicasting.
by Cradarc
Thu Jan 14, 2016 9:42 pm UTC
Forum: The Help Desk
Topic: Wifi mysteriously broadcasting while disabled
Replies: 6
Views: 4083

Re: Wifi mysteriously broadcasting while disabled

Wireshark is sniffing wifi signals only. I'm also connected wirelessly to the network. I don't see why I would be picking up ethernet signals.
by Cradarc
Thu Jan 14, 2016 5:00 am UTC
Forum: The Help Desk
Topic: Wifi mysteriously broadcasting while disabled
Replies: 6
Views: 4083

Wifi mysteriously broadcasting while disabled

My parents have a Dell desktop computer that came with with a wireless adapter. It is connected to the home router via Ethernet cable. To save power, I decided to disable the Wifi adapter when I set up the computer for them. While connected to their network today, I opened up Wireshark on my laptop ...
by Cradarc
Fri Jan 08, 2016 10:51 pm UTC
Forum: Logic Puzzles
Topic: Blue Eyes with Superrationality
Replies: 48
Views: 10630

Re: Blue Eyes with Superrationality

Superrationality is irrelevant when you're not playing against an opponent. After the Guru speaks, there is a deterministic sequence of events that progress in the following days. These events are dependent on the eye color distribution of the population. You are allowed to observe the sequence of e...
by Cradarc
Tue Jan 05, 2016 4:18 am UTC
Forum: News & Articles
Topic: Police misbehavior thread
Replies: 6957
Views: 1115992

Re: Police misbehavior thread

Old news article, but more hopeful than the things people usually talk about:
http://www.contracostatimes.com/news/ci_26482775/use-deadly-force-by-police-disappears-richmond-streets
by Cradarc
Sat Jan 02, 2016 10:24 pm UTC
Forum: Mathematics
Topic: Recursive Circle Packing
Replies: 4
Views: 1613

Re: Recursive Circle Packing

Considering only the points on the square's edge is a good strategy. I never thought about that. Looking only at the circles along the line y = x. If the nth largest circle has radius R(n), then we have R(k+1) = (3 - 2*sqrt(2))*R(k-1). So every number of the form 0.5*(3-2*sqrt(2)) k-1 can be reached...
by Cradarc
Sat Jan 02, 2016 7:52 pm UTC
Forum: Mathematics
Topic: Recursive Circle Packing
Replies: 4
Views: 1613

Recursive Circle Packing

Define the unit square with vertices {(0,0), (0,1), (1,1), (1,0)}. We want to fill this square with circles in a systematic manner as follows: 1. Pick the largest real number, r, such that 0<r<=0.5 and at least one circle of radius r can be placed inside the square without overlapping existing circl...
by Cradarc
Fri Jan 01, 2016 8:20 am UTC
Forum: News & Articles
Topic: Police misbehavior thread
Replies: 6957
Views: 1115992

Re: Police misbehavior thread

If it was just "basic human psychology", we'd see rates of black cops killing unarmed white teenagers at similarly disproportionate rates to what we see from white cops killing unarmed black teenagers. We don't see anything remotely like that, though, which is just one of the many differe...
by Cradarc
Fri Jan 01, 2016 12:05 am UTC
Forum: News & Articles
Topic: Police misbehavior thread
Replies: 6957
Views: 1115992

Re: Police misbehavior thread

The reason I brought up the gun thing is not to downplay the problem of police brutality. Rather, I think a culture that embraces firearms will inevitably breed police who are trigger happy. How can we teach people the horrible ramifications that can result from firing a gun when they are raised in ...
by Cradarc
Thu Dec 31, 2015 9:59 pm UTC
Forum: News & Articles
Topic: Police misbehavior thread
Replies: 6957
Views: 1115992

Re: Police misbehavior thread

My thoughts regarding the Tamir Rice tragedy: Yes, the officer was too quick to use lethal force, but I don't think it is reasonable to call it racism. Have you guys seen the "toy gun"? http://gotnews.com/wp-content/uploads/2014/11/Tamirs-Gun.jpg I don't know about you, but that looks awf...
by Cradarc
Mon Dec 28, 2015 9:28 pm UTC
Forum: Logic Puzzles
Topic: Escape the bear in the circle?
Replies: 22
Views: 6118

Re: Escape the bear in the circle?

This is because your strategy would push the person closer and closer to the boundary. Even while moving in a circle, the bear can position itself to force the tangential direction of the prey's circular path to move towards the boundary. The tangential direction of the person's path, by definition...
by Cradarc
Sun Dec 27, 2015 7:17 pm UTC
Forum: Logic Puzzles
Topic: Escape the bear in the circle?
Replies: 22
Views: 6118

Re: Escape the bear in the circle?

The strategy for the prey is to move around in a circle, always going in the direction away from the bear (that is, consider the radial line through the circle centre and the prey which splits the plane into two halves, and the prey moves in the direction of the half not containing the bear). The p...
by Cradarc
Sat Dec 26, 2015 8:11 pm UTC
Forum: Logic Puzzles
Topic: Escape the bear in the circle?
Replies: 22
Views: 6118

Re: Escape the bear in the circle?

The explanations Notzeb linked to are suspiciously like the Zeno's paradox. At every step, the lion/bear gets closer to the person, yet it never fully overlap the person. The engineer inside me is grinding his teeth at that. I say we throw those mathematicians into the ring and see if they can pull ...
by Cradarc
Fri Dec 25, 2015 7:02 pm UTC
Forum: Logic Puzzles
Topic: Escape the bear in the circle?
Replies: 22
Views: 6118

Re: Escape the bear in the circle?

Bear always wins. Suppose at time T = 0, bear is located at the origin and person is at (1,0). Coordinate system is arbitrary. Consider the possible positions at time T = t, where t is infinitesimally larger than 0. If v = velocity of the person, let r = v/t. So at T = t, the person can be ...
by Cradarc
Thu Dec 24, 2015 7:40 pm UTC
Forum: Science
Topic: How does two black holes orbit each other?
Replies: 14
Views: 2516

Re: How does two black holes orbit each other?

Interesting. Thanks for the clarification. Does that mean, theoretically, if we dropped a point mass in the perfect spot, it would be completely stationary because the gravitational pull from each black hole would cancel?
by Cradarc
Thu Dec 24, 2015 3:01 am UTC
Forum: Science
Topic: How does two black holes orbit each other?
Replies: 14
Views: 2516

How does two black holes orbit each other?

So I came across a wikipedia article on binary black holes.
I don't have much background in astrophysics, but I seem to recall black holes are like a bottomless pit in space-time. If that is the case, how can two black holes orbit? Shouldn't they be so massive that they're effectively stationary?
by Cradarc
Thu Dec 24, 2015 2:53 am UTC
Forum: News & Articles
Topic: 2016 US Presidential Election
Replies: 8482
Views: 1149853

Re: 2016 US Presidential Election

Even if Trump wins the GOP nomination, he will never win the presidency. The fact that the USA has not fallen apart means a plurality of the population are not Trump supporters. Many people like to keep silent until it actually matters. It's just a circus show at the moment.
by Cradarc
Tue Dec 22, 2015 5:41 am UTC
Forum: Science
Topic: Data presentation (Graphical design guru needed!)
Replies: 8
Views: 4331

Re: Data presentation (Graphical design guru needed!)

Here's my two cents: 1. If all your data is binned, you should make it clear by making all of them bar graphs. Right now, I'm getting the impression A is a continuous variable, but B and C are discrete. 2. If B and C are undesirable, make them darker, subdued colors: gray, brown, dark red, etc. If A...
by Cradarc
Wed Dec 16, 2015 3:17 am UTC
Forum: Logic Puzzles
Topic: The Two Oracles - a statistics problem
Replies: 74
Views: 13689

Re: The Two Oracles - a statistics problem

rom a mathematical standpoint where outcomes aren't predetermined, all the outcomes of rolling dice will have probability 1/6. A noiseless oracle with complete information will give 1/6. A mathematical model that does the impossible (such as knowing $real_probability after getting 0.9 and 0.75 as i...
by Cradarc
Mon Dec 14, 2015 10:46 pm UTC
Forum: News & Articles
Topic: Obama finally, finally comes for your guns
Replies: 86
Views: 18002

Re: Obama finally, finally comes for your guns

How on earth would a private seller check to see if someone is on the no fly list, when you can't even check to see if YOU are on the no fly list*? How could that even work? I'm guessing it would be like a background check on a secure government database. It won't explicitly say the person is on a ...
by Cradarc
Mon Dec 14, 2015 10:36 pm UTC
Forum: Logic Puzzles
Topic: The Two Oracles - a statistics problem
Replies: 74
Views: 13689

Re: The Two Oracles - a statistics problem

That certainty is a probability. Probabilities are not just about things that might happen in the future - they can also apply to something that has already happened (or, equivalently, are already determined). Yes, but the certainty is a probability that you are correct about the event . It's not a...
by Cradarc
Sat Dec 12, 2015 9:24 am UTC
Forum: Science
Topic: Best way to get electrical power out of a tealight candle?
Replies: 18
Views: 5267

Re: Best way to get electrical power out of a tealight candl

The candle is our only source of energy, but we have access to any "reasonably complex" device. Can we ask for a new battery or is that too complex? How about something that happen to include a lot of copper and zinc and a tub of brine? If we ask for a nuclear reactor, we might be able to ...
by Cradarc
Sat Dec 12, 2015 9:10 am UTC
Forum: Logic Puzzles
Topic: Factorally growing data storage
Replies: 3
Views: 2685

Re: Factorally growing data storage

Why is this in Logic Puzzles? It makes no sense to talk about bits when you are storing information as cards. As douglasm pointed out, you are still bit constrained if you want to create these cards abstractly. Physical "cards" are way too big to compete with the data density of modern ele...
by Cradarc
Thu Dec 10, 2015 6:37 am UTC
Forum: Serious Business
Topic: Should all public libraries be closed?
Replies: 59
Views: 20866

Re: Should all public libraries be closed?

I think the main problem with e-books is that they depend heavily on electricity and the internet. 1. What if you lived in a part of the world where there is little internet infrastructure? Sure, the government can give our e-book hardware for free, but you can't "check out" new books with...
by Cradarc
Thu Dec 10, 2015 6:01 am UTC
Forum: Logic Puzzles
Topic: Pennies in Boxes
Replies: 85
Views: 51813

Re: Pennies in Boxes

The no fire rule is pretty stupid and makes little sense. 1. Ship the box out to some place where bonfires are allowed, burn it down, then ship the pennies back.You just need to rent a freight truck for a couple days. 2. Bring carts of small boxes inside your home, and burn through the cardboard on ...
by Cradarc
Tue Dec 08, 2015 6:57 pm UTC
Forum: Logic Puzzles
Topic: The Two Oracles - a statistics problem
Replies: 74
Views: 13689

Re: The Two Oracles - a statistics problem

What's the point of going to the oracle if the event isn't "predetermined"? If the oracles, themselves, do not know the outcome with 100% certainty, the only way they are different than the king is their knowledge of hidden variables. If I recall correctly, Bayesian probability always has ...
by Cradarc
Tue Dec 08, 2015 3:13 am UTC
Forum: Logic Puzzles
Topic: The Two Oracles - a statistics problem
Replies: 74
Views: 13689

Re: The Two Oracles - a statistics problem

It's a good analogy, but if you mean to use the value as the probability, I don't think it's quite that simple. If we get 0.9 for the first value, can we deduce a probability from that? Not really - it depends what the signal to noise ratio is. There is no probability to deduce. You know the signal...
by Cradarc
Sat Dec 05, 2015 12:18 am UTC
Forum: Serious Business
Topic: Social Justice: Noble goal?
Replies: 109
Views: 26717

Re: Social Justice: Noble goal?

Well, you can talk to a particular person when they do something inappropriate. That's not really the same as a pre-emptive banning, or whatever, but it seems unlikely that any amount of protesting will be effective at fixing that particular issue. I wonder about this in other circumstances as well...

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