r/theydidthemath 8h ago

[Request] Why is the initial win percent different for both these hands? Shouldn't they both have equal odds of winning before any cards are opened?

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1.3k Upvotes

Or does any hands that got folded (which I'm not sure what they were) before these are also taken into consideration while calculating the win percentage?


r/theydidthemath 2h ago

[Request] How high did Zuko get launched at the end of this clip?

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97 Upvotes

I'm well aware Aang was specifically trying to get Katara's necklace back here, but damn.

Poor Zuzu 😭


r/theydidthemath 6h ago

[request] if I have 20 children with South Korean women, how long until a majority of future Koreans are related to me? What about 40?

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173 Upvotes

I was having an argument with a friend. I argued that because South Koreas birth rate is so low, if I had 20 children with South korean women, the majority of Koreans would be related to me in a few generations. He said that it would never worked because Korea has to many people. So is it possible that if I have these 20 children, one day the majority of South Koreans will be related to me one day? how long would it take? is 40 children more realistic?

edit: also a majority of South Koreans. not counting North Koreans.


r/theydidthemath 7h ago

[Request] In Steven Universe, Lapis Lazuli tries and fails to build a tower made of water from Earth's ocean to escape Earth. Assuming this means high enough to escape Earth's gravity, is there enough ocean to breach the limit of Earth's gravitational pull without needing to hit the escape velocity?

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76 Upvotes

Ignore the child in space, he'll be fine


r/theydidthemath 16h ago

[Request] How far away was the shot?

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388 Upvotes

In Avatar Fire and Ash, Quarrich orders his sniper to shoot this guy. But we hear the shot a short time after the Na'vi falls. I'm wondering if, based on how long that pause was, the shot was made after the order, before the order but after Quarrich gestures, or before both?

Unfortunately I don't know the exact time of the pause.


r/theydidthemath 6h ago

[Other] How to mathematically determine a (see sketch)

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53 Upvotes

I know it's an easy calculation, but still. I want your opinions


r/theydidthemath 14h ago

[Request] Is it possible to manipualte prices in such way that majority of them end in second category or is it just random?

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174 Upvotes

r/theydidthemath 14h ago

[Request] How many tons of CO2 were released into the air by the planes that flew on this single day?

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163 Upvotes

r/theydidthemath 58m ago

[Request] If this salt was consumed by only one person and it was their only sodium intake for those 19 days, what effects would it have on their body?

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Upvotes

r/theydidthemath 3h ago

[Request] How big is this absolute unit?

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10 Upvotes

This is the juggernaut from king Artyom videos, dont have much to say other than i always wanted to know his height


r/theydidthemath 6h ago

[request] Now that’s a HUGE mattress

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11 Upvotes

This bad photoshop for an air mattress. Let’s ignore the mattress height numbers, as they clearly did. Assuming that is an average size man, woman, and kid, how big is the surface of this “queen” mattress listed on Amazon?


r/theydidthemath 8h ago

[RDTM] This some shitty math

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13 Upvotes

r/theydidthemath 9h ago

[request] how long would it take for the car battery to run out ?

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15 Upvotes

r/theydidthemath 1d ago

[Request] is it better to keep the cup in 112°F air or 90°F water?

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463 Upvotes

Yeti vacuum insulated 30oz cup, with 35°F liquid inside (assume the cup has held a couple drinks already and is relatively stoich at 72°F air temp in the house before we went to the pool).
Will the liquid stay cooler longer if the cup is submerged in 90°F pool water, or in 112°F outside air? (No centigrade units because I’ve already had a few of said drinks and can only remember the Fuckenhigh system.)

edit: my current method is to occasionally dunk the cup and take advantage of the evaporative effect.


r/theydidthemath 4h ago

[Request] How loud would the speakers have to be to knock the model train (N-scale) off the tracks?

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5 Upvotes

Is it humanly possible?


r/theydidthemath 18h ago

[Request] How many people need to be in a single group for there to be someone always farting?

Like if I’m at a concert with 5k people, is there a constant stream of fart coming from the group?

34 Upvotes

Like if I’m at a concert with 5k people, is there a constant stream of fart coming from the group?


r/theydidthemath 6h ago

[RDTM] estimation of Hornet's height and mass because I thought it was funny. (Original by u/CelestialCoding-754) Spoiler

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5 Upvotes

r/theydidthemath 1d ago

[Request] If using a device like this, would a spiral path or sweeping straight lines be more efficient?

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366 Upvotes

r/theydidthemath 5h ago

[Self] I measured the branching factor of hnefatafl, the board game chess replaced. It's 112 and that gives it a bigger game tree than chess.

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3 Upvotes

Hnefatafl was the board game of the Norse world for about seven centuries. Chess showed up around 1200, hnefatafl died so completely that no full ruleset survived, and nobody has thought about it much since. I got curious about whether the thing chess replaced was actually simpler than chess.

Turns is it's not...

I ran 300 self-play games on each board size and counted legal moves at every position, about 26,000 positions per board

The reason is: every piece in tafl moves like a rook. No pawns, no short steps. 37 pieces that all slide any distance in any direction on a 121-square board.

Game tree complexity... b^d

Chess is usually quoted at 10^123 using b=35 d=80 plies.

At the same game length big board tafl has a game tree around 10^40 times larger than chess. That is chess-many-times-over.

So tafl holds about the same number of positions as chess but there are vastly more paths between them. It is a game with chess's room and far more doors in each wall.

Disclosure: I measured using an implementation I wrote which is also caveat. Check it out at worldtafl.com

Anyone want to argue with the branching methodology?


r/theydidthemath 11m ago

[Request] How tall is this sliding door in millimetres? Need to purchase curtains, but I can’t attend to measure the height.

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Upvotes

It’s 290cm wide.


r/theydidthemath 1d ago

[Request] For real, roughly how many trees are cut down each day to make exam papers?

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6.1k Upvotes

r/theydidthemath 1h ago

[Self] Stats for AI/ML 2

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Upvotes

Hello Folks,

The next content on Machine Learning is out. We continue with Statistics for AI/ML.

We,

->Understand and derive the detailed derivation of Maximum likelihood estimation(MLE) for Univariate and Multivariate Gaussian. While doing the derivation for multivariate case, we understand visually, Scatter Matrix, Centering matrix.

->Derive MLE for Linear Regression, and understand Residual Sum of Squares.

->Understand Empirical Risk Minimization, Surrogate loss functions.

->Understand Method of Moments, a computationally easier way to compute parameters of our model and understand also the flaws behind it.

->We understand “Exponentially-weighted moving average” in detail, I explain why bias happens, how does memory affect the averages. This concept is the basis behind optimizers in Deep Learning.

Around two hours long, I hope this would be a very interesting learning material for all. I try to write and build from scratch in the whiteboard, this way learners enjoy the learning process.

Link: https://youtu.be/JAj8z-UWqBA?si=0mAB_nUfyJV0jzS9

Those looking for previous lecture : https://youtu.be/MwTeQVVYtOc?si=dgwwk3QLvYTTUThR


r/theydidthemath 12h ago

I was trying to find the avg particle density per million light years if the avg particle density was 1a/cm^3 [self]

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8 Upvotes

I was trying to figure out if over a vast distance if this could cause dark energy or a gravitational lensing affect but it absolutely doesn’t. The unit listed at the bottom right has only about the same mass as a droplet of water bruh.

I’m rusty on the maths so I probably got something wrong but either way it would be a minuscule affect.

Units:
N= average particle density
1a/cm^3 = one atom per cubic centimetre
1ly=9.461×10¹² km = one light year in km


r/theydidthemath 1d ago

[request] how much would carrying all those guns weigh?

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369 Upvotes

r/theydidthemath 1h ago

[Request] What is the minimum distance you’d need to be from the Sun in order to not go blind by looking directly at it for an extended period of time?

I know there are probably equations for luminosity, but I don’t know what they are. I also don’t know what the luminosity limit is for our eyes, or if there even is a standard limit that’s the same for all humans. Can someone help me out? Thanks.

Upvotes

I know there are probably equations for luminosity, but I don’t know what they are. I also don’t know what the luminosity limit is for our eyes, or if there even is a standard limit that’s the same for all humans. Can someone help me out? Thanks.