XKCD: It's more than a comic

I feel that a vacuum like that would act like a ramjet. It can't exactly contain that massive volume of air that it's sucking in, so it'd have to expel it. If the rate of expulsion is anywhere near the rate of intake, it would turn into a makeshift rocket.

... We already have those. They're called jet engines.

And they sometimes suck in birds too. That's usually not good for the plane.

You probably mean turbojet. A ramjet uses its own speed to get the air in, that's why it doesn't work at low speeds.

Yeah, I mixed up my jet propulsion systems.

Was the comic huge for anyone else yesterday? As in, one panel taking up multiple screens? Today it is back to normal apparently.

Yes, I had that bug too.

First I thought that was intentional.

Judging by reddit it was like that for everyone. I think what happened is that while there is normally a big version you can access by changing the image url (can't remember what you add) this time only that version was uploaded.

That was a bug? This being xkcd, and considering the subject of the strip, I assumed that was part of the joke. Actually I thought that "joke" was funnier than the actual joke about a vacuum.

Reverse Poe's Law meets True Art Is Incomprehensible

Let's also add Mistaken for Exhibit to the mix

edited 20th Apr '17 5:38:25 AM by blkwhtrbbt

Brickman: Same here. Oh well.

I thought it was a joke about reading the comic through binoculars, lol.

Survivorship bias and the legitimate business plan of buying lottery tickets

Hmm, could you calculate a point where the amount of money invested in tickets no longer weighs up against the potential profit, on average? How many tickets should you buy before giving up?

Mathematically? At zero. It is never good odds to buy lottery tickets unless the ratio of the jackpot to the ticket price is greater than the odds of winning, taking into account the chance of splitting the jackpot AND the taxes on the prize.

Lotteries are a tax on people who are bad at math.

edited 21st Apr '17 2:36:46 PM by Fighteer

Plus have you ever seen what happens to people who win lotteries? I know I don't want to end up like that.

It's windfall spending. People who don't live with that kind of money don't know what to do with it.

Also all their long lost third cousins come out of the woodwork.

Yeah, it's easy to judge people who win a jackpot and spend it all on pointless luxury only to end up worse than before, but for a lot of people, it's one of the only instances of luxury they've every gotten. When you live paycheck to paycheck, moderation isn't ever an issue.

I disagree with that assessment. I'd argue that the people most likely to win lotteries are the kind of people who frequently but lottery tickets, and people who frequently buy lottery tickets are likely to be people who are bad at managing money.

I'd also argue that your interpretation is a lot more judgemental- it's being judgemental against basically everyone instead of judging a handful of people who we already know for a fact have a history of bad economic decisions.

edited 21st Apr '17 11:16:52 PM by Gilphon

The other exception are the occasional mathematician who exploits the posted rules. I'm too lazy to look up the details, but there's a Texas female mathematician who makes a fair amount of money on scratch-off tickets every year. Basically, her system relies on that the larger non-grand prizes are geographically spread out and that information on who has won is publicly reported. So she adjusts her ticket-buying habits based on the areas that have a higher number amount of prize money for the remaining number of tickets.

I almost want to say it's a sort of Monty Haul problem approach. She targets areas where more doors have been opened, showing there's no car.

It's Monty Hall, named after the host of the TV show where the problem became famous. It would be more amusing if it was Monty Haul, though, so fair play.

Speaking of the Monty Hall problem, would it work for answering a multiple choice question? My theory was that if I arbitrarily choose an answer before I read the question, and then after reading the question eliminate answers I know to be incorrect, then if the answer that I randomly chose in the beginning is one of the remaining options, I should choose another answer. The idea being that since I made the first choice before I read the question, it should be less likely that I chose the right answer than when I later make an educated guess after eliminating options. Does that make sense, or was I just wasting my time?

I tried it on the Bar exam, but the precise situation where it mattered only came up like 5 times.

Not the same thing, because you'll always have some idea of which is the right or wrong answer, or you won't have any way of knowing which the right answer is. With the Monty Hall problem, you open a door and either the prize is behind it or it isn't. With a multiple choice quiz, you either know whether the answer you chose is correct (and thus don't need to apply Monty Hall) or you have no idea whether it's correct or not, in which case you still can't apply Monty Hall.

But you can know what other answers are incorrect, which will affect your probability of choosing the right answer.

That said, upon some thought I guess it wouldn't work because unlike the actual Monty Hall situation, you can and will eliminate the answer you chose fairly regularly. Monty Hall works because a) the presenter knows the right answer, and b) the presenter will never choose to eliminate the initial guess.

edited 22nd Apr '17 1:08:42 AM by Clarste

Theoretically, it works, but the gains you'd get from that aren't large enough to really matter- If, for example, there are four choices, and you can eliminate one of ones you didn't initially choose, that method only makes you ~4% more likely to guess the right answer. ^note  Guessing from the three remaining will no guidance: 33.3%. Monty Halling: 37.5%

If you can eliminate all but one of the answers you didn't initially choose, the numbers look better, but that situation is even less to come up frequently enough to make it really worth the effort.

edited 22nd Apr '17 1:11:17 AM by Gilphon