Pdf Definition and 328 Threads

Homework Statement Let f(x)=x/8 be the density of X on [0,4], zero elsewhere. a) Show that f(x) is a valid density and compute E(X) b) Define Y=1/X. Calculate E(Y) c) Determine the density function for Y The Attempt at a Solution a) is just really basic. I've solved that one. b)...

What's the best portable device for reading mathematical PDF files? - one that would show equations and graphs clearly? I'm not particularly interested in the general field of electronic books or wireless connectivity, but It would be nice to have portable device for the many free math PDFs...

Hello, I have a simple question regarding limits. I have attached this question as a pdf for reasons of accuracy (i can latex to pdf but haven't learned how to work with Mathjax directly here) Regs, DeusAbs

Hello, I'm trying to calculate Fisher information (and eventually the Cramer-Rao lower bound) for this particular pdf with Mathematica: \text{pte}[t,\Theta ] = \frac{P_{\text{ec}}}{\tau _d-\tau _r}\left[e^{\frac{-(t-\Theta )}{\tau _d}}-e^{\frac{-(t-\Theta )}{\tau _r}}\right]...

Hi, all. I happened to think about a problem about conditional PDF: x_2=x_1+a, x_1 \approx \mathcal{N}(0,1), a \approx \mathcal{N}(0,1) so the conditional PDF of f(x_2|x_1), f(x_1|x_2) would both be f(x_2|x_1)=f(x_1|x_2)=\frac{1}{\sqrt{2\pi}}\exp{(-\frac{(x_1-x_2)^2}{2})} And it is clear...

Any suggestion on a free program to convert Word to PDF. I was playing around and I got malware that I am still trying to clean up. Thanks

Hi I am looking for free software that can transform Word Doc to PDF. Maybe PDF back to Word Doc. Any suggestion on which one is good? Thanks Alan

The following question appeared on a practice exam: For f(x,y) = 24xy if 0<x+y<1 , 0<x,y 0 elsewhere find Cov(X,Y) I used Cov(X,Y) = E(XY) - E(X)E(Y) to calculate covariance, with E(XY) = \int^{1}_{0}\int^{1-y}_{0}24x^{2}y^{2}dxdy but for some reason I didn't get the...

I'm writting my paper and need to extract some paragraph out of pdf materials, but the pdf can not be copied, so I need to convert them to word so that I can edit the text. They said pdf can be saved as word document using adobe so I don’t have to use another tool, but I have no idea how to...

Hi, I have K i.i.d. exponentially distributed random variables with mean unity. I need to find the CDF and PDF of the summation of the largest two random variables. How can I do that? The problem in this case is that the combinations are not independent. Thanks in advance

Homework Statement I am doing a practice final exam in preparation of my actual final exam next week. Here is the link. I am doing problem number 2. http://www.math.stevens.edu/~ifloresc/Teaching/2011-2012/MA222S12/Final_Exam_Summer2011.pdf The Attempt at a Solution So this seems...

Ok, this one's got me stumped! Let's take as an example the probability density function for a random variable X so that: f(x) = \frac{4}{3x^{3}} 1≤x<2 f(x) = \frac{x}{12} 2≤x≤4 f(x) = 0 So the CDF for this variable comes out as: F(x) = \frac{-2}{3x^{2}} 1≤x<2 F(x) =...

Homework Statement Find λ given that the joint PDF of random variables X, Y, is given by: f(x,y)=\lambda x y^{2} where 0\leq x\leq y\leq 1 and 0 otherwise I have two questions: 1) How do I graph this? I'm not sure how to approach the inequality and graphing. What does this inequality...

Hi I want to generate a set of random numbers according to a specific distribution, namely given by f(v) \propto v^3\exp(-v^2 C) where C is a constant. It is clear how to do it with a distribution already implemented in Mathematica...

Hi, I'm having a problem with a MATLAB assignment in my probability class. It has to do with finding the joint and marginal PDFs of a pair of random variables. I understand this stuff on paper, but for some reason this assignment is giving me problems since I don't have a good idea of how the...

Hi, I have this random variable: Z=\left(\sum_{m=1}^NX_m^{-1}\right)^{-1} where Xm are i.i.d. exponential random variables with parameter 1, i.e. the PDF of these random variables is: f_{X_m}(x)=e^{-x} How can I find the CDF, PDF, and the MGF of Z? Thanks

Hi guys, I'm really stuck on the following questions, not sure as to how to approach it: Let X and Y be random variables for which the joint pdf is as follows: f(x,y) = 2(x+y) for 0 <= x <= y <= 1 and 0 otherwise. Find the pdf of Z = X + Y And also: Suppose that X is a random variable for...

Homework Statement Find the expected value of cos(A+B) where A is a constant and B is a random variable with a pdf f(b). Present the answer in terms of f(b). The Attempt at a Solution I don't know how far I can go with the answer -- I have tried for a bit now to remove an integral with no...

One document I need to rotate by 180° and another I need to delete every other page (don't ask), is this possible with any free editing software? Thanks Dan

Suppose I have a regular histogram, I can normalize it by dividing the frequency counts by the total number of counts (at least I believe that's all you need to do). What you're left with should be an approximation to the underlying PDF (probability density function). What I'm asking is how...

Hi guys, I'm trying to put pdf science textbooks on to a kindle. They have difficult equations and subscripts/superscripts and pictures of atoms and things which however I try seem to become a jumble. So far I have tried: 1. Using Calibre - dodgy results, equations handled very badly 2...

(the following is Mathematica code) For the rice pdf... P(x)=(x/σ^2) BesselI[0, x (ν/σ^2)] Exp[-(x^2 + ν^2)/(2 σ^2)] ...the Second raw moment is given by doing the integral... Integrate[(x^3/σ^2) BesselI[0, x (ν/σ^2)] Exp[-(x^2 + ν^2)/(2 σ^2)], {x, 0, Infinity}] While the answer...

Homework Statement Define X to be an n-vector of jointly continuous random variables X1, ..., Xn with joint pdf f(x) mapping R^n to R. Let A be an invertible nxn matrix and set Y=AX+b. I want to derive the pdf of f(y) in terms of f(x), the original pdf. Homework Equations The...

Homework Statement A penny is flipped until we see the first head, and flips are assumed to be independent. For each tail we observe before the first head, the value of a continuous random variable with uniform PDF over the interval [0,3] is generated. Let the RV X be the sum of all the...

How can I get this to not wrap outside of my pdf $ \left(-\frac{1}{6 a}(-2 a (-2 + k) + \frac{2\ 2^{1/3} a \left(-3 + a (1 + k)^2\right)}{\left(9 a^2 (-2 + k)-2 a^3 (1 + k)^3 + 3 \sqrt{3} \sqrt{a^3 \left(4 + 4 a^2 (1 + k)^3-a \left(-8 + 20 k + k^2\right)\right)}\right)^{1/3}} + 2^{2/3} \left(9...

Homework Statement The n random variables X_{1}, X_{2},..., X_{n} are mutually independent and distributed with the probability density f(x)=\frac{1}{\pi(1+x^{2})} i) Find the probability density of the average Y=\frac{1}{n}\Sigma^{i=1}_{n}X_{i} ii) Explain why it does not converge...

Given $u_t+u_x\cos t=u.$ a) Find the solution with $u(x,0)=f(x).$ b) If $f(x)=\left\{\begin{array}{cl}\cos^2x,&\text{if }-\frac\pi2\le x\le\frac\pi2,\\ 0,&\text{in the rest}.\end{array}\right.$ Describe $u(x,t)$ for $t\ge0.$ I have to use Fourier transform, but don't know how to apply it for...

$u_t-u_{xx}=0,$ $x\in\mathbb R,$ $t>0$ and $u(x,0)=e^{-x^2}.$ By applying Fourier transform on $t$ I have $\dfrac{\partial }{\partial t}F(u)+{{\omega }^{2}}F(u)=0,$ the solution of the latter equation is $F(u)(\omega,t)=ce^{-\omega^2t},$ now by applying the initial condition I have...

Let me start out and say I'm cheap so I would prefer not to buy an iPad or a Samsung Galaxy tablet. I'm looking for an eReader that does okay on reading the two-column scientific journal format. I don't care about any other features, battery life, etc. I've read people complain about all...

Homework Statement A Normally distributed random variable with mean μ has a probability density function given by _ρ_...*...((-ρ2(x-μ)2)/2δ) √2∏δ|...e^ Homework Equations Its standard deviation is given by: A)ρ2/δ B)δ/ρ C)√δ|/ρ D)ρ/√δ| E)√δ|/2ρ The Attempt at a Solution...

I have a need for software that will convert a .PDF Adobe Acrobat Version 8 file to text that can be imported into MS Word. I do not want a scanning imaging solution, for instance MS Word, Document Imaging. Too many scan errors can result, slowing things down, because of scanning errors that...

I want to get a program to edit pdf files. I notice there are still the old 6.0 standard edition available very cheap. Any short coming get that as I am too cheap to get the latest or even the 9 version. I am not trying to do video and all the fancy stuff, just want to create document with...

Hi guys. I have a test tomorrow and I am trying to work out the problems on the review sheet, but I can't figure out this one dealing with pdf and cdf. Roll 2 fair dice and call each outcome (i,j) where i,j = 1,2,...6. Define: X= {i+j if i+j ≤ 6 ; abs.value(i-j) otherwise} A) Find...

Homework Statement The probability density function of the random variables X and Y are given by: f_1(x)= \begin{cases} 2 & -\frac{1}{4}\le x\le \frac{1}{4} \\ 0 & \text{elsewhere} \end{cases} and f_2(y) \begin{cases} \frac{1}{2} & 0\le y \le 2 \\ 0 & \text{elsewhere} \end{cases}...

Let X~N(μ,σ²). Find the PDF of Y=X^3. X is distributed normally with mean mu and variance sigma squared. PDF=probability density function. How would you go about solving this, I am fairly inexperienced with this stuff.

Homework Statement I have been given a joint PDF for X and Y, with ranges Y>X≥0. I need to find the E(x) and E(y). Homework Equations I know E(x) = ∫(x)*(f(x,y) dx and E(y) = ∫(y)*(f(x,y)) dyThe Attempt at a Solution For ∫x*f(x,y) dx, i used the limits = x to ∞ For ∫y*f(x,y) dy, i used the...

Homework Statement Show that E[Y^4] = 3, where Y~N(0,1) Homework Equations E[(Y-mu)^4]/[E(Y-mu)^2]^2 = 3 E(Y^4) = 1/sprt(2pi)*intregral (y^4)*e^(-y^2/2) The Attempt at a Solution I have expanded and simplified the first equation above and cannot get it to equal 3. I think it's...

The random variable X has the PDF fX(x) = cx^-2 if 1 < x < 2; 0 otherwise: (a) Determine the value c (b) Let A be the event fX > 1.5. Calculate the conditional expectation and the conditional variance of X given A. I'm not understanding the concept of conditional pdf's. Can someone show me the...

If the probability density of X is given by f(x) = {2(1 − x) for 0 ≤ x ≤ 1 {0 otherwise (a) Find the probability density function of Y1 = 2X − 1. I do not know how to start this problem can someone please help. Is there a formula that I am missing from my notes to solve this problem?

Homework Statement Find the value of k that makes this a probability density function. The question does not specify whether X and Y are independent or dependent. That is actually another part this question. Homework Equations Let X and Y have a joint density function given by f(x,y)...

Homework Statement D = (L + E) / S Where L, E, and S are mutually independent random variables that are each normally distributed. I need to find (symbolically), the conditional PDF f(d|s). Homework Equations The Attempt at a Solution Not sure what to do with so many...

1) see pdf for question 2 I'm unsure how to calculate the force at the fulcrum since its not in equilibrium. I thought maybe i would add the two forces together, but that doesn't seem right. 2) so this question asks for what forces need to be applied at points A and B and i understand...

Homework Statement I am currently doing my thesis, and the gravimetric analysis data I receive from a partner laboratory is in the form of tables in PDF Files. I need to plot the data. It would be tedious if I copy and paste every cell manually, so I decided to automate it using a program...

when i want to compile this error appear and it cannot open the PDF could't find input index file: C:\users\farbod\Desktop\1f\1f\PAPER L nor C:\Users\farbod\Desktop\1f\1f\PAPER L.idx.Usage: C:\Program Files (x86)\MiKTeX 2.9\miktex\bin\makeindex.exe [-ilqrcgLT] [-s sty] [-o ind] [-t...

Hi,guys. I'm doing my paper with my teacher now,we are trying to convert 1500's of pdf files to word 2010 that has not been labeled correctly so using the built in feature that acrobat has does not allow the tables and colums to convert without going all over the place. Is there anyway to do...

Hello I am having trouble deriving using block matrix notation the conditional pdf of two joint Gaussian vectors: I assume that it just involves some re-arranging of eq 1 (attatched) but am unsure if taking the inverse of the resultant matrix in eq 1 is valid and if the order of...

Hi all, I am having trouble with the concept of joint pdf's. For example - a set Z1,Z2,...ZN are each gaussian rv. Let Z1~N(0,1), let X be +1 or -1 each with probability 0.5. Z2=Z1X1, so Z2 is ~N(0,1). (I assume this to be As Z2 is just Z1 multiplied by a simple factor, an instance...

I did try using Zotero (as suggested from http://www.quora.com/Is-there-a-way-to-easily-rename-an-academic-pdf-to-author-names+year+title), but it wasn't able to find names for half of my PDF files.

If the set of real numbers is considered as a sample space with the Borel sigma algebra for its events, and also as an observation space with the same sigma algebra, is a pdf or pmf a kind of random variable? That is, are they measurable functions?

Could someone please advise me how to put the integral from + to - infinity notation used $ exp{-1/2(y-x)^2(A^-1) + x^2(B)^-1}dx Into the form k1 $ exp[-k2(x-k3)^2]dx using the fact that $exp(-1/2x^2)dx = 2pi^1/2 I have encountered this problem when trying to derive the conditional...