To be Devil's Advocate:
Given that the rest written in Comic Sans, it may be an early elementary school exercise, aimed at teaching kids to do multiplications. In this case, it's tolerable and/or defensible to find a simplification for pi.
That said, making pi equal to 3 would have been more accurate for that...
...if they're above average, I think they'll figure out the explicitly defined variable. I think the instructor is trying to make sure this problem doesn't require a calculator and figured defining pi as 5 makes it clear that you can treat it as a whole number. 3 would be more accurate and just as easy, but meh idk that this is that great of a blunder.
You can be a smart kid and not realize that adults are lying.
I remember the Peas and the Punnett Square. Sure, mendelian genetics explains pea plant colors, but doesn't explain dog fur colors. Just providing a footnote that more completed genetics exists would have been nice.
Or it's from an ME. They seldom can remember the rounded value of Pi, but they're pretty sure it's somewhere between 3 and 4. But you probably should use 5 just to be safe.............
In astronomy, pi=1 or 10, depending on whether you’re trying to over or under estimate something. Because when you’re trying to estimate distances measured in millions of light years, the difference between 3 and 10 is just one or two orders of magnitude on a small number. It’s pretty common for astronomers to do napkin math by rounding every single number to the nearest zero. 91k becomes 100k for instance. Because the napkin math estimations are just trying to gauge whether some celestial event or object is a thousand light years away, ten thousand, a hundred thousand, etc… And pi becomes 10, because that’s the nearest round number.
Depends on the level of precision you need. If I want the volume in a 500 foot long, 3 inch pipe to roughly estimate how much supply I need to order, I wouldn't need a calculator. It would very roughly be 90-95 ft3. (Divide 500 by 4 two times and multiple by 3)
Then I would spend 5 minutes double checking myself haha.
I think you're overthinking it. The first thing you're told when you learn algebra is that a letter represents a number and you can say "let a equal (number), b equal (number)..." so you can let pi equal whatever you want for the purposes of one simple problem.
Well, if we want to be pedantic, they never said that h is the height and r is the radius of the base circle. They could be just random numbers.
Also, since we never calculate with all the digits of pi, it is not any less weird to round to the nearest 5 and say that it's 5, than to the nearest 0.01 and saying it's 3.14. It just has a higher amount of rounding error.
Except pi isn't a variable. It is a known value that we refer to as pi for convenience, and pi is a fundamental aspect of how a circle is. Saying "let pi equal 5" is all fine and well but is physically impossible, you will not be determining the volume of a cylinder if you let pi equal 5, because the ratio of a circle does not equal 5, it equals 3.14
But I suppose part of solving a maths problem is staying within the confines of the question and listening to instructions, so if someone says "using pi equals 5", I'd just use pi equals five and take my point with grace.
I think it’s actually a very interesting question. Pi does not equal 5 in our universe, but perhaps we can think of a meaningful universe where it does? Perhaps some mathematicians/physicists can chime in?
Idk, if you want to test people on how they understand formulae and order of operations without letting them just punch it into a calculator. The actual math isn't hard, but if you don't get substituting values into an equation then it's not trivial
It's not just about haveing a calculator, it's also that it's faster and more convenient if you can do simple sums like this in your head. It also means you can sanity check the numbers your calculator gives you to make sure you didn't make a mistake entering the sum.
To your point below about products having their unit cost displayed, more than once I've seen that just be wrong, so I wouldn't rely on it. Make sure you can check it in your head.
But if you want to buy only half a kg, you don't know how much it costs (if you dont know basic maths)- because it only lists the price for a full kg. Do you start pulling out your Excel for that?
If you really wanted to be through you'd start at a point, integrate out along dr for a line, then integrate in a circle through dtheta to derive the area before doing the rest
The answer is substantially different though. 3141 units (rounded correctly) vs 5000.
That's a significant margin that even working it out in your head is not forgiving enough to cover.
Good thing I don't need to do math at work. Saw a video the other day where someone said "10x400" and was shocked that they couldn't instantly multiply by a power of ten. And then I walked into this.
Numbers are symbolic, I’d say it’s not a bad piece of homework to supplement a lesson that numbers are to be respected but ALSO to always know that they mean nothing without context.
We can appreciate the beauty of infinity in memorizing pi, but the reality we live in demands actions of whatever the fuck it is we redefine volition, will, or passion to.
I think people can be so much more, but my idea of more is tainted by the values I have. Not everyone would agree with the idea that we all deserve to live.
Survival of the fittest, they support indirectly. With actions that include the advent of modern advertising. The CIA(?) experiment on attention, catalyzed by the creation of lsd in the knowledge-obtaining-goal of understanding the mechanics of attention, were directly related to the patriot act.
I’m not claiming anything other than the fact that our “leaders,” have used their knowledge of attention spans to sway the, “masses.” The rest of us.
How do you think of the, “rest of us?”
I hope you teach your children that, and that math is the beauty we’ve come to understand in our millennia of evolutionary timescales, of fucking struggle.
You have within you, much.
Do not waste the years of before, do something to help. Not your country, but your reality. The outside. You’re something. Not “nothing but a part of.” There’s so much in the word, “just.”
That’s all I have to say. Just that. Not much. Just a tiny little wall. Sorry. I write, and I rant, and I let go. Please don’t ban me. I matter and I’m not hateful. I’m sorry.
I truly wonder what sprouted this comment. We're all taking about how this one teacher butchered math by rounding π completely incorrect and you're posting this half-rambling, idk if medicaments-induced, pseudo intellectual crap. This has 0 to do with it, go to some DMT board.
Nobody knows how to think like a dyscalculic at all haha... it's just a little symbol thingy... it doesn't have to be pi. Just like X is a little symbol thingy... the x is now just kind of a table right now...... it's just a little symbol thingy and it means five it's not that difficult. Lmao
Yes it does have to be pi because that's the formula for the volume of a cylinder. If you take a simple, cylindrical glass or container and measure it and apply the formula with pi, you'll see that you'll get the correct volume of the container. If you just want your kids to calculate a random x that's 5* 10 *10 *10 just tell them to do that, don't give them a made up formula, it's not that difficult.
Mathematically, no, it does not. We make up the definitions. If you wanted to see what the consequences of a, I don't know, 5-dimensional universe with Pi set to 5.65 were, you can do that. These are scribbles on pages, there is literally nothing stopping you.
Academically, what's stopping you is whether these calculations are useful. The only problem I see here is that it's kind of misleading to imply to someone that Pi is something it conventionally isn't. But even then, I think I'd respect the mathematician who could recognize Pi as a symbolic name for, usually, one particular transcendental constant a little bit more than one who refused to even entertain the idea. Like, imagination is important to mathematics, too.
And to be clear, "let Pi = 3.14" is also incorrect. It is closer than 5, but it is still infinitely wrong.
[edit] And also, I was imagining this question was for a younger audience. Reading it again, I'm not going to pretend I know what's going on up there.
Pi is now 5 due to inflation
Having Pi equal five definitely does not help the world go round.
Wouldn’t it make it seem like a bigger place?
Maybe on paper if you want to look at it from that angle.
Tangentially, I like the pun, but now you're just being obtuse.
To be Devil's Advocate:
Given that the rest written in Comic Sans, it may be an early elementary school exercise, aimed at teaching kids to do multiplications. In this case, it's tolerable and/or defensible to find a simplification for pi.
That said, making pi equal to 3 would have been more accurate for that...
Unless the kid is even slightly above average and finds the idea that pi equaling 5 confusing.
...if they're above average, I think they'll figure out the explicitly defined variable. I think the instructor is trying to make sure this problem doesn't require a calculator and figured defining pi as 5 makes it clear that you can treat it as a whole number. 3 would be more accurate and just as easy, but meh idk that this is that great of a blunder.
You can be a smart kid and not realize that adults are lying.
I remember the Peas and the Punnett Square. Sure, mendelian genetics explains pea plant colors, but doesn't explain dog fur colors. Just providing a footnote that more completed genetics exists would have been nice.
Heh nice try but we don't write textbooks or exams for the outliers.
Or it's from an ME. They seldom can remember the rounded value of Pi, but they're pretty sure it's somewhere between 3 and 4. But you probably should use 5 just to be safe.............
https://www.youtube.com/watch?v=L1eegVTwDS0
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https://www.piped.video/watch?v=L1eegVTwDS0
Piped is a privacy-respecting open-source alternative frontend to YouTube.
I'm open-source; check me out at GitHub.
That's a dumb way of teaching and you are a dumb devils advocate for saying it. Go to H E double hockey sticks.
Even in engineering it is common to just round pi to 3 and quickly estimate whatever it is your doing.
In astronomy, pi=1 or 10, depending on whether you’re trying to over or under estimate something. Because when you’re trying to estimate distances measured in millions of light years, the difference between 3 and 10 is just one or two orders of magnitude on a small number. It’s pretty common for astronomers to do napkin math by rounding every single number to the nearest zero. 91k becomes 100k for instance. Because the napkin math estimations are just trying to gauge whether some celestial event or object is a thousand light years away, ten thousand, a hundred thousand, etc… And pi becomes 10, because that’s the nearest round number.
Fermi Estimation. Where you're dealing with something so big, you're just interested in the magnitude.
"About yay big."
Excuse me what? I've been an engineer for a decade and have never met anyone that would do that. We have calculators.
I think they mean napkin math. Like you're in a meeting and they ask for a general idea if something will work or not
I suppose. I'm still internally outraged and haven't run into such a situation before, but I accept this.
To be fair most of the situations where I've run into this have never involved pi, and sometimes it's just qualitative.
That makes sense. I feel like if you're at the point where pi is meaningfully involved, you should probably do your math.
We all have phones with calculators, don't really need to do napkin math anymore
Depends on the level of precision you need. If I want the volume in a 500 foot long, 3 inch pipe to roughly estimate how much supply I need to order, I wouldn't need a calculator. It would very roughly be 90-95 ft3. (Divide 500 by 4 two times and multiple by 3)
Then I would spend 5 minutes double checking myself haha.
I feel like a proper engineer would call only going two places past the decimal "rounding pie".
I need a new maitre'd for a restaurant I am opening. How busy are you?
Not very, but I'll require lots of pay.
How does 1 million a minute sound?
Ill take it!
I'll give you the hardest 30 minutes I've worked in my life, and then retire.
So you do know how to act like a decent human. Damn. Well the restaurant closed. I guess you can just be nice for your own esteem now.
Nope. I had sold my house to move and told the kids already. Now I'm jaded I just lost out on 30 mill and we're homeless. I'll be an ass forever, now.
That's how you know math is OP when you can calculate volumes in parallel worlds where circles don't even looks like circles
Ah, Manhattan. Where pi = 4, and circles are diamonds.
Bringing new meaning to the phrase "assume cows are spherical"
"Assume a spherical cow, which for our purposes can be approximated as a cube."
They're just rounding up from "3."
And not that pussy rounding up where you go up by only 1, oh no, we’re rounding up 2 baby.
The value of Euler's number is now 4.
Damn inflation is everywhere now, even the transcendentals :'(
pi, as it turns out, is just the friends we made along the way
Wow, 5 friends is more than what I have!
This is how the wealthy calculate their tax exemptions.
Due to inflation, they now have a bigger pi.
This guy has think tank fellowship written all over them.
A bigger pi-ness.
With π=5 maths break down completely. If π=5, then e^(5i) = -1, meaning -1 = cos(5) + i * sin(5), or -1 ≈ 0.284 - 0.959 i
Intel®️ inside
Wow, that takes me back - you're referring to the floating point bug from ...98?
It's posts like these that makes me think we're all old here on Lemmy and then I get a response from someone who tells me they're 18...
665.999999657838 the floating point number of the beast
Yup. Pentium FDIV bug.
I think you're overthinking it. The first thing you're told when you learn algebra is that a letter represents a number and you can say "let a equal (number), b equal (number)..." so you can let pi equal whatever you want for the purposes of one simple problem.
But the question is saying to find the volume of a cylinder. Which its clearly wrong.
Well, if we want to be pedantic, they never said that h is the height and r is the radius of the base circle. They could be just random numbers.
Also, since we never calculate with all the digits of pi, it is not any less weird to round to the nearest 5 and say that it's 5, than to the nearest 0.01 and saying it's 3.14. It just has a higher amount of rounding error.
Why are we upset by rounding to the nearest 5 for elementary schoolers when we round to 10 m/s/s for gravity in collegiate physics classes anyway?
It's not even a bad thing to do for quick mental calculations, if you know that you will overshoot. Multiplying by 5 is easy.
Or as I like to call pi...the little symbol thingy. But exactly yes, you get it.
Except pi isn't a variable. It is a known value that we refer to as pi for convenience, and pi is a fundamental aspect of how a circle is. Saying "let pi equal 5" is all fine and well but is physically impossible, you will not be determining the volume of a cylinder if you let pi equal 5, because the ratio of a circle does not equal 5, it equals 3.14
But I suppose part of solving a maths problem is staying within the confines of the question and listening to instructions, so if someone says "using pi equals 5", I'd just use pi equals five and take my point with grace.
Okay but they didn't say 3.14 they made a little symbol thingy
Well I suppose for example rounding to the nearest integer is a method of implying "let 1.8 = 2", no? Not too outlandish, I don't think.
Maybe e is 5, too?
I think it’s actually a very interesting question. Pi does not equal 5 in our universe, but perhaps we can think of a meaningful universe where it does? Perhaps some mathematicians/physicists can chime in?
It would be theoretically possible in a universe based upon non-Euclidean geometry.
Idk, if you want to test people on how they understand formulae and order of operations without letting them just punch it into a calculator. The actual math isn't hard, but if you don't get substituting values into an equation then it's not trivial
Just let π be 3 ...
Or have them learn how to use a calculator at the same time.
Your life is easier and better if you can do this kind of simple math in your head.
Oh don't you try to sell me on the "you won't always have a calculator in your pocket" thing. I have fucking Excel in my pocket.
It's not just about haveing a calculator, it's also that it's faster and more convenient if you can do simple sums like this in your head. It also means you can sanity check the numbers your calculator gives you to make sure you didn't make a mistake entering the sum.
To your point below about products having their unit cost displayed, more than once I've seen that just be wrong, so I wouldn't rely on it. Make sure you can check it in your head.
Who really wants to use Excel to figure out if the 24-pack of Coca-Cola or the 3 12 packs is a better deal?
I don't need to, there's a legal requirement to print prices per liter or kg on every price tag here.
Does this requirement exist for toilet paper? Because I don't know what the hell is considered a better deal based on all the marketing.
But if you want to buy only half a kg, you don't know how much it costs (if you dont know basic maths)- because it only lists the price for a full kg. Do you start pulling out your Excel for that?
When you want students to not use calculators but still rate a question for 10 second answer.
"One! Two! FIVE!" "Three, Sire!" "THREE!"
That just means the curvature of spacetime is negative.
Teaching them to to obey dumb instructions from incompetent bosses.
Very useful skill.
Assume the earth is a flat disc . . .
I've moved on to a no earth society.
It's called philosophy haha
π = 5 for very small values of r.
New New math
Hooray for new math
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Hooray for new math
Piped is a privacy-respecting open-source alternative frontend to YouTube.
I'm open-source; check me out at GitHub.
Reminds me of Bo Burnham's song New Math
Here is an alternative Piped link(s):
New Math
Piped is a privacy-respecting open-source alternative frontend to YouTube.
I'm open-source; check me out at GitHub.
Ah, Indiana math.
https://en.wikipedia.org/wiki/Indiana_pi_bill
I would be a smartass and leave Pi as a factor throughout and in the answer. I'm used to doing that in Calculus anyways.
V = πr^2^h
V = π⋅10^2^⋅10
V = π⋅100⋅10
V = π1000
BONUS SOLUTION:
V =∫
0^10^ A⋅h dhA = ∫
0^10^ 2πr drV= ∫
0^10^ ∫0^10^ h⋅2πr dr dhh is a constant for A's integral so we can safely move it into V's integral
V= ∫
0^10^ h⋅∫0^10^ 2πr dr dhπ is a constant so we can safely remove it from A's integral
A = π⋅∫
0^10^ 2r drA = π⋅[r^2^]
0^10^A = π⋅( [10^2^] - [0^2^] )
A = π10^2^
A = π100
V = ∫
0^10^ h⋅π100 dhπ100 is a constant so we can safely remove it from V's integral
V = π100⋅∫
0^10^ h dhV = π100⋅[h]
0^10^V = π100⋅([10] - [0])
V = π100⋅10
V = π1000
It goes a lot deeper but I'm not bored enough for that, yet.
EDIT: Hang on. I'm wrong with that height integral. Can somebody help remind me?
If you really wanted to be through you'd start at a point, integrate out along dr for a line, then integrate in a circle through dtheta to derive the area before doing the rest
This physics class?
Astronomy.
π = 5 if you round to the nearest 5
Makes me miss the days of 22/7.
The answer is substantially different though. 3141 units (rounded correctly) vs 5000. That's a significant margin that even working it out in your head is not forgiving enough to cover.
Unless I fucked up.
...in spacetime with high curvature?
Doesn't curvature cause pi to not be a constant? And wouldn't it be negative curvature that would cause it to be higher than euclidean space?
pi was mutable all along
Pi = phi
500? But I just woke up and I take sleeping pills so my brain might not be working.
5*10**2*10 = 5*10*10*10 = 5000Good thing I don't need to do math at work. Saw a video the other day where someone said "10x400" and was shocked that they couldn't instantly multiply by a power of ten. And then I walked into this.
I think I just got it! Pi is very close to 5 dB (~4.9714 dB)
Nother one of them "uncertified teachers" huh
suspension of belief is also being tested, I see.
So is their answer just 5,000?
Yes about 2000 too much.
Numbers are symbolic, I’d say it’s not a bad piece of homework to supplement a lesson that numbers are to be respected but ALSO to always know that they mean nothing without context.
We can appreciate the beauty of infinity in memorizing pi, but the reality we live in demands actions of whatever the fuck it is we redefine volition, will, or passion to.
I think people can be so much more, but my idea of more is tainted by the values I have. Not everyone would agree with the idea that we all deserve to live.
Survival of the fittest, they support indirectly. With actions that include the advent of modern advertising. The CIA(?) experiment on attention, catalyzed by the creation of lsd in the knowledge-obtaining-goal of understanding the mechanics of attention, were directly related to the patriot act.
I’m not claiming anything other than the fact that our “leaders,” have used their knowledge of attention spans to sway the, “masses.” The rest of us.
How do you think of the, “rest of us?”
I hope you teach your children that, and that math is the beauty we’ve come to understand in our millennia of evolutionary timescales, of fucking struggle.
You have within you, much.
Do not waste the years of before, do something to help. Not your country, but your reality. The outside. You’re something. Not “nothing but a part of.” There’s so much in the word, “just.”
That’s all I have to say. Just that. Not much. Just a tiny little wall. Sorry. I write, and I rant, and I let go. Please don’t ban me. I matter and I’m not hateful. I’m sorry.
I truly wonder what sprouted this comment. We're all taking about how this one teacher butchered math by rounding π completely incorrect and you're posting this half-rambling, idk if medicaments-induced, pseudo intellectual crap. This has 0 to do with it, go to some DMT board.
Reading that comment was a wild ride! It started off innocuous enough, but really went off the rails FAST!
Nobody knows how to think like a dyscalculic at all haha... it's just a little symbol thingy... it doesn't have to be pi. Just like X is a little symbol thingy... the x is now just kind of a table right now...... it's just a little symbol thingy and it means five it's not that difficult. Lmao
Here's a little LPT for you: you can be correct without being an obnoxious douchebag about it.
Yeah, "symbol thingy" is setting me off rn.
The only thing that can help me is filing my taxes incorrectly.
Your message reads kinda douchey.
Yes it does have to be pi because that's the formula for the volume of a cylinder. If you take a simple, cylindrical glass or container and measure it and apply the formula with pi, you'll see that you'll get the correct volume of the container. If you just want your kids to calculate a random x that's 5* 10 *10 *10 just tell them to do that, don't give them a made up formula, it's not that difficult.
Mathematically, no, it does not. We make up the definitions. If you wanted to see what the consequences of a, I don't know, 5-dimensional universe with Pi set to 5.65 were, you can do that. These are scribbles on pages, there is literally nothing stopping you.
Academically, what's stopping you is whether these calculations are useful. The only problem I see here is that it's kind of misleading to imply to someone that Pi is something it conventionally isn't. But even then, I think I'd respect the mathematician who could recognize Pi as a symbolic name for, usually, one particular transcendental constant a little bit more than one who refused to even entertain the idea. Like, imagination is important to mathematics, too.
And to be clear, "let Pi = 3.14" is also incorrect. It is closer than 5, but it is still infinitely wrong.
[edit] And also, I was imagining this question was for a younger audience. Reading it again, I'm not going to pretend I know what's going on up there.
Well, let me put it another way. You don't need to have an opinion on everything. It's okay to not understand something and not have an opinion on it.
I'm dyscalculic... I'm allowed to have an opinion on it this is how my brain works.
Also if we can't say that pi is just a little symbol thingy then I guess we better stop using fucking exclamation marks everywhere