/sci/ - Science & Math

>>10851188
>>10851188
just integrate a normal distribution with sigma=2.56 and mean=315 between 314 and 322. wolfram alpha can do this

>>10851188
it must be at least 7

>>10851202
How do you put that into wolfram alpha? I paid for the premium app but i don't know how to use it, where can I learn about other distributions like hypergeometic, binomial and hypergemetric? I do not understand

>>10851212
>I paid for the premium app but i don't know how to use it
god is there a better analogy for people who try to buy into STEM ability.
sorry im not making fun of you, i dont know how to either

>>10851212
>>10851240
sorry meant normal approxmiation method I put hypergeometric twice

>>10851212
this turned out to be harder than it should have. wolfram apparently is making wolframalpha less user friendly.

anyway the answer is .6488:
wolframalpha.com/input/?i=normal+distribution&assumption={"F",+"NormalProbabilities",+"mu"}+->"315"&assumption={"F",+"NormalProbabilities",+"sigma"}+->"2.56"&assumption={"F",+"NormalProbabilities",+"l"}+->"314"&assumption={"F",+"NormalProbabilities",+"r"}+->"322"&assumption={"C",+"normal+distribution"}+->+{"Formula",+"dflt"}

>>10851264
And how can I do it on my own? I am studying and I need to learn about those probability distributions and how to calculate them but when I watch khanacademy and so on I get confused and can't remember it all. Can you please help me?

>>10851188
impossible to say since we do not know the distribution

>>10851264
This might seem pterry crazy but... maybe if you can't solve the problem you could just threaten to make the entire planet flat? All I'm saying is it used to be flat in medieval times so all you have to do is recreate that feeling and maybe it would work?

>>10851271
definite gaussian integrals and error functions are hard to do by hand. i think almost every stats textbook includes a table in the back to crib digits from, and you can learn the tricks to be able to figure out arbitrary definite gaussian integrals and error function stuff using those tables. they aren't hard and you can sort of figure them out by mapping the standard mu=0 and sigma=1 to arbitrary gaussians by simple translation/multiplying the x-axis/normalization

i forgot that all because i use ROOT or mathematica for that kind of stuff instead of relying on paper-printed lookup tables. but in principle one can do it easily with undergrad-level understanding plus a 1-page printed lookup table

>>10851282
I don't know what any of that means I haven't learned it I just need to figure out how to get binomial, normal and hypergeometric distribution probabilities.

>>10851276
i am sure for potato chip manufacturers, there are many independent sources of uncertainties, so the Central Limit Theorem applies, therefore it is a normal distribution by common sense.

one could test this empirically if you have doubts. but i am sure that if regulators imposed this particular 2.56 gram standard deviation rule, then they made sure it was gaussian already (otherwise the rule doesn't make much sense)

>>10851285
just buy a stats 101 textbook. i don't even remember the author of mine. but they all cover that; this is all undergrad level stats so any book should be fine. also, the OP question sounds more like gaussian statistics, i.e. a normal distribution, not any of what you listed

>>10851291
Well this particular question is, I'm doing a practice test to prepare but the other questions are hard for me too.

Such as:
>Three coins are tossed 175 times and the number of times that 3 tails comes up is noted. Calcyulate the probability that 3 heads came up less than 22 times, using the normal approximation.
>Determine the probability that 3 tails came up more than 34 times using the normal approximation

>>10851296
well then anon, i can't tell you there's any easy way to get good at statistics except by reading the textbook and actually learning the material. if you aren't allowed to do wolfram alpha to cut out the lookup table work or numerical integration drudgery, you better start working on it. stats seems trivial but it actually isn't.

it gets easier only once you are allowed to just "know" things like "oh that will be gaussian, here is the gaussian integral to do" which i knew because it just is intuitive to me at this point (and i implicitly invoked the central limit theorem like this anon was pointing out: >>10851276 so some conceptual understanding is involved as well). anyhow, you need to learn the nitty-gritty of gaussian integrals as well as the concepts. you can forget the nitty-gritty later depending on what you plan to work on in the future, but the concepts are key.

>>10851318
I find it so difficult to remember this shit though, it's dumb because in real world applications I would just be able to google it

>>10851188

You must be at least 10 to post in this board. GTFO my board retard.

>>10851338
this is a real world application though. potato chip companies probably hire a statistician or to to make sure they are complying with rules. google doesn’t replace having a person with actual knowledge

>>10851188
it depends completely on the distribution, if it's a normal distribution just eyeballing the numbers it should be about 50%

>>10851345
To determine the probability I would be able to google it though or someone smarter than me would have already solved it anyway.

Please how can I remember it so I can pass this course

>>10851348
“about 50%” doesn’t cut it anon. your first decimal place is off. the answer is .6488 to four decimal places, so you are basically totally wrong

>>10851350
you learn the concepts, that’s how. i know zoomers like to think math and science are like memorizing pokémon but it turns out life doesn’t work that way

ACtually I don't think you can get around calculating or looking up a table in this case.

You need to do what >>10851202 said , it's quite easy except you can't calculate the integral by hand with normal tools and you most likely won't be required to

>>10851373
yes, as i already said here:
>>10851282
zoomers just don’t read the thread they’re posting in, do they

>>10851369
>just learn bro

great advice thanks

>>10851350
Kek

>>10851386
it is good advice. don't cut corners.

if you are posting ironically and you mean some retard level shit like
>/sci/ needs to redpill me on the way to game the system, surely there is some shortcut cheater method!
then anyone who thinks that is retarded. one part of becoming good at math or science is having respect for the depth of the ideas involved, and if you think you can "game" it, then you deserve to fail

>>10851403
I just need to do the course i dont care about stats otherwise, it's too hard for me

>>10851414
then learn to do the exercises cus the exam will usually be like them u brainlet

>>10851460
That's why I need someone to explain to me how to solve them I dont get it so far.

For example when you're inputting it into the Z-score why do you have to add .5 and subtract .5 randomly? I know it has something to do with the mean but I don't get it

>>10851474
the only thing close to adding/subtracting 0.5 I can think of is if you are approximating some distribution with e.g the normal and want do do a continuity correction or something

>>10851506
Yes exactly, when do I need to do that? I dont understand it

>>10851514
to improve the approximation by pushing the gaussian graph a bit to the side so it fits the discrete bars of the other distribution better