• klu9@lemmy.ca
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    16 days ago

    Some bureaucrats in Mexico City tried this years ago.

    An important ring road had two lanes in each direction. To increase its capacity, they didn’t actually widen the road; they just repainted the lane markings to turn two lanes into three, and claimed a 50% capacity increase!

    Everyone immediately screamed about being crammed together just centimetres apart, accidents increased and the city officials quickly u-turned; they repainted to have just 2 lanes in each direction again.

    But they then tried to claim that as that was a 33% decrease, and that because they had earlier increased it 50%, that meant they had achieved a net 17% increase in the road’s capacity!

  • adarza@lemmy.ca
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    16 days ago

    pegglegg back in fifth grade: ‘why i need to learn this math stuff. i aint never gunna use it’

      • adarza@lemmy.ca
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        16 days ago

        you still need to know what buttons to push on the magic box, and in what order…

          • nomy@lemmy.zip
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            16 days ago

            “It’s not like you’ll regularly have a little box in your pocket with access to the sum of all of the knowledge in the world but you’ll have to sift through an equal amount of incorrect knowledge and have the ability to differentiate the two.”

    • Bone@lemmy.world
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      16 days ago

      That kind of math didn’t start for me until letters started showing up in it. This is basic shit though!

  • dis_honestfamiliar@lemmy.sdf.org
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    16 days ago

    I might as well throw the same comment in here. You learn this pretty quickly when you bet on meme stocks. Down 90% then up 100% I can assure you, you are no where near where you started.

    • jonne@infosec.pub
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      16 days ago

      Same with crypto. You’ll get a notification something went down 10%, then up again 10%, but if you zoom out you see it’s just been slowly going down on average since the last huge spike.

    • jacksilver@lemmy.world
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      16 days ago

      This is clearly about the US stock market crashing. In that case it’s always the days gain/loss, in which case Yang is the only person who is right.

      This is important because a lot of people saw “down 10%” and now “up 10%” without realizing that’s still day over day loss.

      • HollowNaught@lemmy.world
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        14 days ago

        While the idea put forward by him is correct, stating that 100-10=90+9=99 is just entirely incorrect, hence why I’m saying they’re both somewhat correct

  • CheeseNoodle@lemmy.world
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    16 days ago

    Not even close to that anyway, the dow jones for example went from 44k to 37k back up to 40k. Still hasn’t even regained half the value it lost.

  • JohnDClay@sh.itjust.works
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    16 days ago

    It’s only the same if it’s up 10% compared to the original number. It all depends on your time period, you could be up 30% compared to 7 years ago.

    • uranibaba@lemmy.world
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      16 days ago

      Tesla stock prices are good example of this. They are down ~50% since december and up ~70% since lowest point in april last year.

  • Treczoks@lemmy.world
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    15 days ago

    Don’t they teach math in the US anymore? Or do you get a pass on basic subjects if you are on the football team?

    • Someonelol@lemmy.dbzer0.com
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      14 days ago

      You get a pass on pretty much every subject because the school’s interested in churning out worker drones rather than thinkers. Do this long enough and you get Trump supporters.

      • Sprawl@lemmy.world
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        14 days ago

        Heck, for a while, we insisted on passing kids no matter what so they weren’t “left behind”.

    • Abnorc@lemm.ee
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      14 days ago

      Practice is important. People definitely learn this level of math, but not using it for years dulls the senses. On top of that, lots of people scrape through school doing the bare minimum. (Not always their fault of course. Not everyone has ample opportunity to excel in school due to a variety of things.) From what I hear, the bar for graduating high school is not incredibly high, so people like this don’t surprise me.

      • Treczoks@lemmy.world
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        14 days ago

        Knowing basic math (and sometimes a bit more) is quite useful in life. I am currently having a beef with my bank who tried to cheat me out of a larger sum. But I know the correct methods and the correct rates, and, of course, the contract. And obviously, it really pisses them off that someone even does the calculations…

    • Captain Aggravated@sh.itjust.works
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      14 days ago

      They teach math from like 6th grade up as if every middle schooler in the land is going to grow up to be a sweater wearing chalkboard writing mathematician when they grow up. It’s taught as a series of arbitrary rules to follow. Here’s some squiggles, and now you do this to the squiggles. NO you don’t do that to the squiggles, do you want to be a ditch digger you fucking waste of sperm. You do THIS to the squiggles. Can’t you FUCKING tell the difference you little cuntpuke? You use the Crendicative property of intiplicity. No, it’s not five, it’s negative three. It’s obviously negative three, What idiot would get five? I know you got five and not some other number because this is designed to be a trick question. There’s only one point in this big long procedure that matters, if you decide correctly you get negative three, if you decide incorrectly you get five. And you got five.

      They do this to you for your entire adolescence.

        • Captain Aggravated@sh.itjust.works
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          14 days ago

          I actually learned math in physics class. Because in physics class, the equations mean something. They represent a relationship between things that you can grasp. There are built-in sniff tests. You can go “Wait, the ball rolled off the table and then…started moving toward the ceiling? That’s not right, where did I…Oh I subtracted a negative number, I should have added a negative number.”

          From Kindergarten up to about middle school, they teach by practical example. “You have two apples, and you buy two more, you have four apples.” “If you have two pizzas, each cut into 8 slices, you eat 5 slices from one and 6 slices from another, how many pizzas do you have left?” That stopped entirely in middle school to be replaced with “Here are abstract rules to apply to abstract numbers, and instead of explaining why here are paragraphs of “proofs” written in a logic system we won’t teach you anything about and therefore mean nothing to you, memorize it verbatim so you can write it on the test.”

          Yeah I’m not compatible with math class as I’ve seen it taught. I can do math when it means something. Arbitrary meaningless bullshit busywork full of gotchas? Nah, I’m not doing it.

        • faythofdragons@slrpnk.net
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          14 days ago

          My third grade teacher told me that negative numbers didn’t exist because having less than zero is impossible. I think I’m justified in being bitter about my education.

      • Someonelol@lemmy.dbzer0.com
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        14 days ago

        Yeah you’re right that they act like everyone’s gonna be a pure mathematician with only abstract applications. I think test standards have kinda fucked with their expectations. I’m sorry you had bad math teachers. Many of them suck at explaining the subject and act like dicks. Get enough of them in school and it’s easy to lose interest in something that’s extremely practical to know later in life.

  • billwashere@lemmy.world
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    16 days ago

    Multiplication is commutative dipshits.

    A x B = B x A

    So 1.1 x .9 is always going to be .99, regardless of the order. Didn’t we learn this in like middle school?

    (Edit … to be clear I’m calling the people in the image dipshits, not the people commenting here).

      • billwashere@lemmy.world
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        16 days ago

        If you increase something by 10% you’re doing this:

        (10% • X) + X

        (.1 • X) + X

        1.1 • X

        So you’re just multiplying the original value by 1.1. Similarly for subtracting 10% you’re multiplying by .9

        So the order in which you add or subtract 10% doesn’t matter. You always get the same number.

  • yarr@feddit.nl
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    15 days ago

    Yeah he totally cooked Yang. That guy has NO IDEA where the 9 came from.

  • driving_crooner@lemmy.eco.br
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    16 days ago

    This is why in forecasting and time series analysis is used the log difference, a 10% increase or decrease on the log scale gives you the same value being added or removed.

      • driving_crooner@lemmy.eco.br
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        16 days ago

        Not really, you do t=n and t=n+1, for n= 1, 2, 3 for a quick view on volatility.

        Then ypu look up for correlations between e[t=n | t= 0, t= 1…] for different Ns. For more I would need to check out my notes

        • embed_me@programming.dev
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          16 days ago

          Oh I was imagining something entirely different. Like a simple logarithmic scale of a signal, I do not know anything about time series analysis. Should’ve kept my mouth shut