Dragneel

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$Mathematics$ Mathematics

Associated with Math.SE; for both general discussion & math qu...

Dragneel

Aug 24, 2018 20:04

I see. So it only works if the function $g(x)$ is a linear, and not exponential.

Dragneel

Aug 24, 2018 19:49

When I said $x=25$ is $50$, I meant $50$%

Dragneel

Aug 24, 2018 19:30

Hey guys, I'm not sure what I'm doing wrong with my calculations here, I'd appreciate help.

We know that given some number $x$ in the range $a$ to $b$ we can work out what percentage of $x$ that is in between $a$ and $b$ with $\text{Percentage}(x,a,b)=\frac{x-a}{b-a}$ as explained in this post https://math.stackexchange.com/q/754156.

Now, given the following function $f(x) = x^2 *10$. The values for the functions are as such
https://gyazo.com/197f5e950772a5844ae509868f0c5ce8

Let us arbitrarily choose $a=10$, $b=40$, and $x=25$ which is $50%$. We can confirm $25$ is $50%$ using the equation

Dragneel

Dec 9, 2017 20:11

Hmm I need a little help with statistics :)
I don't know how to answer the last question because I don't think I was given the Significance Level $\alpha$.
https://i.gyazo.com/af9239d2255e9995b1b1efd60abba0a6.png

Dragneel

Dec 9, 2017 19:05

Fascinating.

Dragneel

Dec 9, 2017 19:04

@user685252 Whoa we have footage of the guy that proved Fermat's last theorem??!

Dragneel

Dec 9, 2017 18:44

That's interesting. Well, don't take it for granted, you're lucky to have a calculator built-in your head ;)

Dragneel

Dec 9, 2017 18:41

@KevinDriscoll Were you careless because you couldn't see the value in mathematics or because it was too easy?

Dragneel

Dec 9, 2017 18:36

Would you guys say you were always talented in the field of mathematics, or did you have to excessively study it and be molded by it before you really understood it.

Dragneel

Dec 8, 2017 20:39

Anyway, I have to go write an exam, see you later, and thanks for the help guys :)

Dragneel

Dec 8, 2017 20:39

True, good observation.

Dragneel

Dec 8, 2017 20:33

@PVAL-inactive Here's how I thought about it. For any integer $n$, $n*16$ seems to result in an integer than ends with either $0,2,4,6,8$, that is, even digits. And since we're looking for $n\equiv 1 (mod 16)$, only odd $n$ integers will satisfy us because of a remainder of $1$.

Dragneel

Dec 8, 2017 20:21

@PVAL-inactive Ah that's interesting. And that's why b is the correct answer, since 50% of the numbers are odd.

Dragneel

Dec 8, 2017 20:01

Hmm does this question make sense to you guys? Apparently the answer is b.
https://i.gyazo.com/60c38343bddc64b20675c8a01021196e.png

Dragneel

Dec 8, 2017 17:38

Okay, just what I thought. Thanks :)

Dragneel

Dec 8, 2017 17:22

Hi guys. Is this valid? I'm skeptical about the $(5^2)^{30}$ because it equals $5^{60}$, and it was $5^{30}$ before. Why would they double the exponent?

https://i.gyazo.com/a0b49487716b1adcf52ebb13ce96e2cd.png

Dragneel

Dec 5, 2017 20:49

Anyone has experience in Test Statistics, involving testing claims about population mean?

Dragneel

Nov 22, 2017 01:56

Let $a_n$ be the sequence with the following recursive definition: $a_1=0$, $a_n=a_{\lfloor \frac{n}{2} \rfloor}+1$.
I'm asked to find the first few values of $a_n$. And they are $0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,...$.
Now I'm asked to find an explicit formula for $a_n$. It says (Hint: first consider the values for $a_n$ when $n$ is a power of $2$). So here's what I got $a_n=\lfloor \log_2 n \rfloor$.

Dragneel

Nov 22, 2017 01:48

Anyone have experience with proving recursive sequences?

Dragneel

Nov 15, 2017 00:54

Hi everyone. I'm a little stuck trying to prove this using induction. The question is:
https://i.gyazo.com/cbeb74502360815b0a80f295ba6ff3c6.png

Here's what I have done so far:
https://i.gyazo.com/8620c000663a6c9cb9efa9ba41e24156.jpg

So basically, I'm stuck at $(-1)^k [\lceil \frac{k}{2} \rceil +(k+1)(-1)]$

Dragneel

Nov 10, 2017 02:35

Not sure how to word it, but referring to the question in my image, $T_0=X_1+X_2+...+X_n$ where every $X$ is a different song. I believe.

Dragneel

Nov 10, 2017 02:32

Umm I think $T_0$ involves multiple items from a sample

Dragneel

Nov 10, 2017 02:30

Ugh question d is actually driving me insane....
I can really use help if anyone knowns about the CLT
https://i.gyazo.com/a4102af279052947dfa43f1682e4a422.png

Dragneel

Nov 10, 2017 00:55

Main what

Dragneel

Nov 10, 2017 00:50

I honestly did

Dragneel

Nov 10, 2017 00:48

Alright I need help understanding this. The theorem in my book doesn't state what $T_0$ is here https://i.gyazo.com/bff2db558f467dbe01bdd16da8a700b3.png

I thought the formula for the Central Limit Theorem was
$\frac{X-\mu}{\frac{\sigma}{\sqrt{n}}}$
but this is telling me there's another formula that looks like this
$\frac{X-n\mu}{n\sigma^2}$?

Dragneel

Nov 9, 2017 23:01

Isn't the Central Limit Theorem the same thing as Confidence Intervals? I'm reading my statistics book and they're similar

Dragneel

Nov 9, 2017 20:37

Not sure if that's what you're looking for.

Dragneel

Nov 9, 2017 20:35

But I haven't found an easy-to-use software

Dragneel

Nov 9, 2017 20:35

I know of a popular Chrome extension here chrome.google.com/webstore/detail/daum-equation-editor/…

Dragneel

Nov 9, 2017 19:56

Wait, I thought you DID know everything.

Dragneel

Oct 31, 2017 20:42

Okay thanks @LeakyNun :)

Dragneel

Oct 31, 2017 20:41

Hi everyone. I made a change of variable $j=i-1$ for the summation in the picture and basically shifted it. My solution is correct right?
https://imgur.com/a/qeuB2

Dragneel

Oct 26, 2017 02:58

There's no way to find the prime decomposition of a large number without a calculator right?

Dragneel

Oct 26, 2017 00:05

Hi everyone. Quick question, do you guys know a quick way of calculating $20 C 2$ without a calculator?

Dragneel

Oct 22, 2017 23:31

You can say $X$ follows a distribution. Like, $X$~$B(n,p)$ which is binomial dist. There's $X$~$nb(r,p)$ which is negative binomial, $X$~$h(n,M,N)$ for hypergeometric etc..

Dragneel

Oct 22, 2017 23:27

Yea i didn't get that at first.

Dragneel

Oct 22, 2017 23:27

Thanks Ted :)

Dragneel

Oct 22, 2017 23:27

@TedShifrin I figured it out. It was asking for the mean-squared value. That is, $E(X^2)$

Dragneel

Oct 22, 2017 23:19

@TedShifrin So, essentially, they're asking for the Median?

Dragneel

Oct 22, 2017 22:51

I just tried submitting the variance and it's incorrect. That's really odd.

Dragneel

Oct 22, 2017 22:50

It asked for the variance in the last question though.

Dragneel

Oct 22, 2017 22:48

What does it mean when you're asked for the "second moment" of a continuous random variable $X$? I'm doing a statistics assignment and came across this question that has me puzzled.
https://imgur.com/a/ymJZC

Dragneel

Oct 21, 2017 18:31

Hmm. That never occurred to me.

Dragneel

Oct 21, 2017 18:31

I'm so excited to fail my Stats midterm (again) this Tuesday :D

Dragneel

Oct 21, 2017 18:05

It's possible, yeah.

Dragneel

Oct 21, 2017 18:05

I'm not too worried about it.

Electrical Engineering

A place to talk with friends from the EE community about vacuu...

Dragneel

Oct 23, 2017 20:51

When converting a truth table into boolean

Dragneel

Oct 23, 2017 20:49

Hi guys. Is the Product of Sums(POS) the complement of Sum of Products(SOP)?

Root Access

For all you Super Users out there. You have backups, right?

Dragneel

Oct 23, 2017 03:16

Sup guys. Anyone have any experience with Combinatorial Circuits?