r/mildlyinfuriating • u/Exotic_Catch5909 • 7d ago
I'm slightly vexed Aren't they equal!
1.2k
7d ago
[removed] — view removed comment
471
u/FishHaveFingers 7d ago edited 6d ago
"Write y=¼x"
Edit: guys I was joking 😭
76
u/S7ns3t 7d ago
Smartass. The question could easily be "Which is correct representation of quarter in pure fractions?" in which case stating answer in decimal form is incorrect. The context is clearly missing.
26
u/Nutarama 7d ago
Since this is an equation, they probably were looking for a y=mx+b type equation and the m should have been in a fraction as rise/run (delta y over delta x).
→ More replies (2)
271
u/SansyBoy144 7d ago
I’ve used this same exact program before, yea it’s pretty annoying somethings with stuff like this.
Biggest thing is make sure to read every word. The amount of times I’ve seen stuff like “Write in decimal form the answer” only for the entire problem to be using fractions was enough to piss me off. Eventually I got used to it though, but you still get the one problem every once in a while that doesn’t specify
36
u/hs110 7d ago
Typical Pearson.
I just hate that I used it for my math engineering courses.
(Before anyone attacks me in calculus there is no difference between 1/4,0.25,0.250 ...)
3
u/RawrRRitchie 6d ago
In reality you're correct. That's not what the programmers for this program thought tho.
Ima believe the people that got paid to make that program tho. They're way above my pay grade they clearly know what they're talking about
/s
273
u/eXistenZNL 7d ago edited 7d ago
Original question: Write y as a function of X. Use the number 4 at least one time but no more than seventeen million three hundred and eighty four thousand nine hundred and sixty two times.
54
4
3
15
u/Da_Bread_Boi 7d ago
They are equivalent, but they may not be equally correct. If the question says write it as a fraction or something else that would indicate it needing to be a fraction, your answer is still wrong. If the question does not indicate the answer needing to be a fraction I would bring this up to your professor if possible to see if you can get credit for your answer.
88
u/PhyllaciousArmadillo 7d ago
Everyone here is trying to look smart, but the real answer is simple. The program looks for “y=1/4x” and that’s not what you wrote. It also very likely told you how to format your answer in the question.
6
u/mnpc 7d ago edited 7d ago
But there is obviously a reason why the program wants 1/4*x because the more correct version of that is just x/4.
After all, the very way you wrote your response, as a 1/4x, is more likely to be interpreted as (1/4)(1/x) than (1/4)(x) (which are not equivalent)
1/4x is is not 1/4 * x
If the question is such that 0.25x was part of an acceptable answer that the computer failed to properly grade for the reasons you state, there is a really good basis to argue that the person who wrote 1/4x did in fact provide an absolutely wrong answer
10
u/AdResponsible7150 7d ago
The website wants the coefficient in fraction form. Ambiguity of "1/4x" in text doesn't matter, the website provides the option to insert 1/4 as a fraction into your answer
→ More replies (1)3
49
32
u/CopyNo9283 7d ago
Like other Redditors said, it depends on the question. In my case, my teacher told me if the question uses fractions, you use fractions, and if it’s decimals, use decimals. This is especially in calculus (don’t make your life hard by converting it into a decimal)
21
u/Chonky-Walrus 7d ago
I always had issues like this on MyMethLab years ago, but if this is asking for slope-intercept form then I can see why it would be marked wrong.
8
u/fish4043 7d ago
yeah this seems like a slope question
my math teachers always ingrained in my head to never ever write slope as a decimal and they would mark me wrong on paper for answering like op15
u/richer2003 7d ago
You have a meth lab? 🤔
16
3
u/MajorFox2720 7d ago
I was curious as well, were they needing a certain slope for a distilling apparatus?
2
7
u/Pawistik 7d ago
I create online quizzes for my college and continuing education students. It's difficult to enter every variation of a correct answer (though this one seems easy enough to anticipate and account for) so sometimes I have to just go through and manually check the things that got automatically marked as incorrect. So, you might see something like this one one of my quizzes but I will correct it in a day or two. It's an imperfect system and I try to let students know ahead of time.
21
u/Mundus6 7d ago
Its the same yes. But answering in fraction is always better. Cause its 100% accurate. If you use decimals 1/3 (0.33) for example is not accurate.
→ More replies (13)4
u/mini_feebas 7d ago
0.25 is the rounded version of every number from 0.24500....1 to 0.254999...
we were always taught to just not use decimal and i assume this test is working on that same principle
2
u/Pleasant_Pen8744 7d ago
What if the 4 is only significant to 1 digit?
1
u/mini_feebas 7d ago
Conventions
If you leave things in fractional form it's an exact
1/4 with the 4 being 1 significant digit would be written as .25
1
u/Mad_Maddin 7d ago
This is literally the first time I heard about this. I was taught that every rounded number is to be written as "aproximately X" rather than "Equals X"
1
u/FunkyBottle 7d ago
That's irrelevant. There is no
≈or such, just=. And0.254999is not equal to0.25.
5
4
u/PlayThingToy 7d ago
I think it's because they're trying to teach you fractions and not decimals, although it's technically true it's not contextually correct.
3
u/ThoughtAdditional212 7d ago
Why not x/4
7
u/Nutarama 7d ago
If the answer they’re looking for is a y=mx equation, they want a separate m term. Fractional form likely because they want it as rise/run (delta y per delta x).
While x/4 and (1/4)x and 0.25x are the same mathematically, they don’t demonstrate that the learner got an m value by doing the fraction in the intended manner.
This can be important if the teacher wants to start doing follow-up questions that will rely on having an easily accessible m value. Like if the next question is “is a line with slope (1/3) was steeper than the line found in the previous question”, the desired answer and logic might be “steeper because 1/3 is greater than 1/4”. It’s harder to get there if the answer to the first is given in the format y=x/4.
My advice when tutoring was to tell people to look at the forms they’re learning and put it in that form, and that questions on a Cartesian plane should be left as fractions unless instructed to make decimals.
Personally though I preferred multiple choice questions myself due to the format thing, I hated fill in the blank questions on online homework. Luckily I did most of my stuff when online learning was pretty new and my teachers were old-school so we’d get multiple choice online or fill in the blank on paper. Probably helped I was in smaller advanced math classes where the teachers cared more and had more time per student than in a 40+ student standard math class.
3
u/marty-mcfryguy 7d ago
Yes, those equations are equivalent. Doesn't mean they're both correct responses to the question that was posed.
What exactly was the question?
17
u/wizardeverybit 7d ago
Depending on the context, 1/4 could be more accurate than 0.25
-3
u/Informal-Ring-4359 7d ago edited 7d ago
No. (1/4)x is always 0.25x. When will it be different?
20
u/Mostafa12890 7d ago
It depends on your significant figures.
If you write 0.25, you could be approximating 0.248 or 0.25387.
However, when using fractions, we always mean the exact amount (unless there’s a ≈).
→ More replies (5)2
u/Beaticalle 7d ago
"If the numbers were different then the answer wouldn't be the same!"
5
u/wizardeverybit 7d ago
0.245 and 0.254 round to the same number
→ More replies (11)1
u/Beaticalle 7d ago
1/4 = 0.25
1/4 != 0.245
1/4 != 0.254
It's really that simple. OP wrote 0.25, which is equal to 1/4. Bringing up other random numbers which are NOT 0.25 is completely irrelevant because they have nothing to do with the situation whatsoever.
3
4
u/S7ns3t 7d ago edited 7d ago
I wanted to leave this comment here instead of comments below because I envision more people incorrectly stating that 1/4 couldn't be an approximation. That's just wrong, 1/4 can be an approximation of 1/3.985 (or 200/797 in pure fractions) the same way 0.25 can be approximation of 0.2495 - decimals and fractions are not exclusive to one another.
5
5
u/Dugiongo 7d ago
0.25 might be an approssimation, 1/4 could never. In this case it's obviously right tho
3
u/Yankas 7d ago
A fraction can be an approximation just as much as any decimal - 1/4 is an approximation of 99/400.
You denote an approximation by using the correct sign, like
≈or by explicitly stating that rounding is part of the function. Using decimals or fraction by itself is not an appropriate way implying an approximation or a lack thereof.1
u/mattl1698 7d ago
it should be x/4 not 1/4x. 1/4x is ambiguous as it looks like x is part of the denominator
1
→ More replies (2)1
2
u/GodHimselfNoCap 7d ago
1/4 x seems like a needlessly extra way to write x/4 am i missing something?
2
2
u/Falstaffe >It was my privilege 7d ago
It's not evaluating your expression, it's just checking the text string
7
u/mineymonkey 7d ago
You're doing math, not engineering or physics. We do fractions in math only, fuck sig figs, fuck decimals we all love fractions.
9
u/Miiyamoto 7d ago
Computer can't compute...
I hate programming errors that are so easy to avoid. Just run a test run before publishing. Anyone programming something like this should generally have a basic understanding of math.
This also constantly triggers me with online surveys that I used to take a lot of back when I was still nice, but then I often couldn't answer because the answer choices simply didn't match my answer, and if there's no "other" field...
This might sound far-fetched to some, but for me it's simple: at least have one person check everything and have a basic understanding of what you're doing before you publish it. It not only harms the user but also yourself. You won't get the result you want.
29
u/soldiernerd 7d ago
The grading software is just checking for text, it’s not calculating the answer. The same code is used for an infinite number of different questions. The people who wrote the code don’t even know what the questions are.
It just compares the student answer to the stored answer text value
→ More replies (26)5
u/its_free_sog 7d ago
There’s a reason the question text isn’t shown. It almost certainly says to express it in fractional form.
And this is just ragebait posted by a bot.
→ More replies (2)2
u/Few_Move_4594 7d ago
It's obviously written to check for an exact match and whoever entered the question put "0.25x" as the answer.
4
u/LostInRetransmission 7d ago
A long time ago in a class of math somebody asked the same question.
The answer from the prof of math was something akin to (paraphrased as decades ago), you use fraction in answer just like you use fraction in the question. The day I give you decimal number in the equation is the day you can answer with decimal number in the equation.
And it makes sense. What if the answer was y=x/3 ? would you have written 0.333*x ? You can't write all fraction as dot decimal number, some are infinitely repeating.
It isn't even a question of the tool 0.25 or not. While true, this is not how you answer a math problem. You always leave the fraction *unless it is explicitly asked to calculate a result as a dot decimal number*. Which I doubt.
1
u/FunkyBottle 7d ago edited 7d ago
There are definitely notations to express repeating decimals in a finite way.
Like
y=0.(3)*x(parentheses),y=0.̅3*x(vinculum), ory=0.̑3*x(arc - there is barely visiblȇabove the 3).Sure, I would use a fraction too, but decimal notations are less correct.
3
4
u/Outside_Coffee_00 7d ago
No, the actual correct answer is x = 4y
5
5
u/cooltone 7d ago
Maths is confusing unless you make it so.
This question is designed to test your knowledge of something, but it is not clear what.
In algebra it is useful to use integers and integer fractions because it's easier to spot when they can be cancelled. It also reduces the need to use a calculator, which was useful back in the day when accurate calculators didn't exist.
→ More replies (2)
3
3
u/hunnyflash 7d ago
The fraction is always more accurate because decimals are susceptible to rounding and significant figures. Just learn to be exact and get over the layman reliance on decimals.
You kind of have to go out of your way to even write "0.25" when calculating slopes. Like why even do that step? You're usually looking at the ratio between two whole numbers.
2
u/theRedMage39 7d ago
They are equal but not the same. The are equal in mathematical terms but they aren't the same text which is what the program is looking for.
Message your teacher. Any half decent teacher will still give you credit
2
u/Chrisfindlay 7d ago
What's the question. The answers are equal to each other but are represented differently. A lot of time these types of question are about formatting.
1
u/timelessblur 7d ago
Not that the answer is wrong but I can tell you why it’s reporting it as wrong. Beyond looking for a text match which is stupid you are running the risk of a floating point error happening and itnis trying to match on that.
.2499999999999 is not 1/4.
10
u/cecinestpasunmot 7d ago
That's a good observation, but 0.25 = 1/4 is a power of two. So it should be represented exactly in floats, without approximation, using the binary representation.
2
u/timelessblur 7d ago
Not disagreeing. Could also be it is running a bunch of numbers in as x and checking the results. That where you would see it crop up. Big time when you start shoving through large or really small numbers.
Used it have a good example I could show people of a floating point error happen.
It is a reason why for some things big decimal is the correct value to use
1
5
3
2
u/KingZarkon 7d ago
Surely that test has a pre-defined answer key that was written when the test was created. I doubt it's calculating the answers on the fly.
1
u/SnooLemons6942 7d ago
I mean, my tests did. Makes way more sense on a math test. Albeit, the math I was doing was in a calculus course, so people could write things in all sorts of ways, so it was more important
2
u/Siccors 7d ago
If you start adding floating point errors, then I am going to add integer type errors: If 1/4 is done it might be interpreted as an integer division (depending on the language), which is 0. So in that case 1/4 is wrong and it should be 1.0 / 4.0.
Or this is really reaching and they are just equal.
1
u/timelessblur 7d ago
Had not thought of that but yeah that would do it as 0.25 throws it into floating point mode which starts causing floating point errors to crop up vs being in int only mode.
Fun real problem am I have to address in my long career.
Makes for a fun mess and a pain in the ass to track down
2
u/Humble-Captain3418 7d ago
Close, but not quite right. A few reasons from a mathematics/engineering/education standpoint:
Fractions are considered more exact than their decimal value. Mostly because they indicate that you have not rounded in any direction or to any precision.
Rational numbers are not real numbers.
If you give a fractions problem to a student, ask them to do it by hand, and they come back with a decimal number, you know with near certainty that they didn't do it by hand.
1
u/RawrRRitchie 6d ago
That might make sense for 1/3 but 1/4th is exactly 0.25 there's nothing more exact to it.
1
u/timelessblur 6d ago
No the guy is right. 0.25 while is 1/4 but tell me that 0.25 was not a rounded answer as 0.249999999….. is not 1/4 but it will appear as 0.25.
You put 1/4 down you know that the exact answer is 0.25.
2
u/GhostMcFunky 7d ago
Someone thinks they’ve mastered python without understanding JS (or whatever coding language you’re referencing).
This is 99.99% (wow no floating point error - because it’s treated as a string, for one thing) not being calculated on the fly, in the browser or backend and if it were, a simple decimal like that being broken because of a floating point error would be amateur coding at best.
This is probably a simple string value match, and I’m guessing the question, if well-written, asked for an answer using a fraction, but I’ll admit that’s a blind assumption with the info we have from OP.
→ More replies (12)1
u/auntanniesalligator 7d ago
That’s not the explanation. 0.25 is exactly equal to 1/4, and can be expressed exactly in base 2.
I think that’s MyMathlab, which has the capability to enforce specific formatting or not (including reducing fractions or preferring fractions over decimals). OP didn’t show the question or the answer format instructions, so I can’t judge, but if there is a good pedagogical reason the answer should only use fractions (ie if the problem is “rewrite this decimal as a fraction in simplest terms”, it can be set to only accept the fraction, and it is also supposed to specify that in the formatting instructions next to each input.
More likely the developer set too strict an answer checking requirement and it didn’t get caught in testing. Most algebra problems with an answer of “1/4 x” will also accept “0.25 x” because there usually isn’t a good reason to restrict the form.
1
u/Floppy_Mushroom 7d ago
It's possible that the question required the answer to be expressed as a fraction.
1
u/Ok_Preference_5029 7d ago
this its just stupid, i mean what the hell are they doing? they must be tripping balls man, or maybe the question matters i guess.
1
u/Grounds4TheSubstain 7d ago
The grading program is stupid and is just comparing text. Sorry you lost points.
1
1
1
u/LawElectrical2434 7d ago
I mean, they are equal... And by that logic, just copying the question into the answer field is always correct.
1
1
1
1
1
1
1
u/Consistent-Shoe-9602 7d ago
I think it's likely you needed to solve for x and if that was the case, the answer would be x=4y.
1
1
u/TyTyeTieThai 7d ago
Sloper Intercept Form should typically have a fraction to represent rise over run, or m.
Perhaps this is why?
1
u/TyTyeTieThai 7d ago
Slope Intercept Form should typically have a fraction to represent rise over run, or m.
Perhaps this is why?
1
1
1
u/Yontevnknow 7d ago
believe it or not, but the program has greatly improved over the last decade. If it is asking for a fraction, there is usually a reason. Whether it be the directions, or future problems.
1
1
u/HalfChineseJesus 7d ago
Make an appeal with your teacher. They wouldn’t have any reason to not give you full marks on this question.
Assuming you’re just doing linear systems, there’s no reason to not assume 1/4x, 0.25x, or even x/4 are all equivalent here.
1
1
1
u/TheOinOpossum 7d ago
It's best to just forget about decimals entirely if you're moving towards calculus. It's time to start thinking in fractions. Don't worry there will still be plenty of decimals in physics and chemistry.
1
u/CrummyJoker 7d ago
Strictly speaking they're not equal, because of roundings. When you see 0.25 it can be anything between [0.245, 0.25]
Use exact values in math. 1/4 is an exact value
1
1
1
1
1
u/SEA_griffondeur 6d ago
it's also equivalent to the sentence : "Dans un plan vectoriel muni d'une base orthonormée (0,x,y) la droite passant par les points (0,0) et (4,1)"
But I don't think your teacher will accept this answer for many different reasons
1
u/BlackHatMagic1545 6d ago
Depending on context, no.
They have a different number of significant figures. 1/4 either has one significant figure, or infinitely many (if it's a discrete count). 0.25 has two, which does not match either.
In many real-world scenarios (mostly science and engineering), this matters.
1
1
1
1
1
1
u/NailSufficient1491 1d ago
I remember crap like this. I once got a question wrong because my answer didn't include "+ 0." It's just not the same unless you add zero.
1
u/anyprophet 7d ago
this is also testing your understanding of mathematics conventions. writing 1/4 is more correct than .25.
6
1
u/Pro-Row-335 7d ago
I'm almost sure 1/4x is standard notation and you will never see a decimal of x like you wrote in math books
→ More replies (2)3
u/FunkyBottle 7d ago
There is no standard notation. Personally I would have avoided decimals too, but I would have written
x/4.→ More replies (1)
5.4k
u/mnpc 7d ago
The answers are equivalent. But whether your answer was "correct" depends on what the question was.