Marginal Definition and 90 Threads

Hi, I have question about finding marginal distributions from 2d marginal pdfs that lead to the probabilities being greater than 1. Question: If we have the joint probability distribution ## f(x, y) = k \text{ for} |x| \leq 0.5 , |y| \leq 0.5 ## and 0 otherwise. I have tried to define a square...

I am curently working on Forecast in cosmology and I didn't grasp very well different details. Forecast allows, wiht Fisher's formalism, to compute constraints on cosmological parameters. I have 2 issues of understanding : 1) Here below a table containing all errors estimated on these...

Homework Statement Homework Equations marginal revenue[/B] (R') is the additional revenue that will be generated by increasing product sales by one unit The Attempt at a Solution I don't know how to start. Q is the number of items sold at price x. y is the marginal cost, the cost of...

Hi, would someone be willing to write a pedagogic article on the Quantum Marginal Problem? Thanks!

Homework Statement f(xy)=49/8*e^(−3.5*y) 0 < y < inf and −y < x < y 0 otherwise a. Find the marginal probability density function of X, fX(x). Enter a formula in the first box, and a number for the second and the third box corresponding to the range of x. Use * for multiplication, / for...

Homework Statement Two components of a laptop computer have the following joint probability density function for their useful lifetimes X and Y (in years): f(xy)=xe^(−x(1+y)) 0 <= x <= y 0 otherwise Find the marginal probability density function of X, fX(x). Enter a formula below. Use * for...

http://www.nature.com/articles/srep35596

Let $$X_1,\dots,X_n$$ be i.i.d $$N(\mu,\sigma^2)$$. What is the marginal pdf of $$\sum_{i=1}^n (X_i-\overline{X})^2$$. I'm guessing it's some sort of chi square distribution but how to find this I am unsure. Thanks

Hello. Can you help me figure out how to pass, integrating, by the marginal cost: $MC_{i}(q)_{i}=q_{i}+10$ to the total cost: $TC=\frac{1} {2}q_i^2+10q_{i}$? $i=1,2$, are the two companies. $q_{i}$ is the quantity. What are the calculations?

Speaking just of long straight wires, not loops, coils or solenoids. Ideal wires have no resistance. Of course they would have no capacitance. And real wires have some very small amount of inductance, no? Firstly, would an ideal wire have some ideal nonzero inductance? Why/why not? After all...

Homework Statement Determine ##P(X<Y|x>0)## Homework Equations X and Y are random variables with the joint density function $$ f_{XY}(x,y)= \begin{cases} 4|xy|,-y<x<y,0<y<1\\ 0,elsewhere \end{cases}$$ The marginal densities are given by $$ f_X(x)=2x\\ f_Y(y)=4y^3 $$ The Attempt at a Solution...

Homework Statement Consider two random variables X and Y with joint PMF given by: PXY(k,L) = 1/(2k+l), for k,l = 1,2,3,... A) Show that X and Y are independent and find the marginal PMFs of X and Y B) Find P(X2 + Y2 ≤ 10) Homework Equations P(A)∩P(B)/P(B) = P(A|B) P(A|B) = P(A) if independent...

If there are X and Y two random variables. The pdf of Y is f(y), and conditional pdf of X is f(x|y). I want to find the marginal CDF of X, the F(x). Is this correct? F(x)=\int^{F(x|y)}_{-\infty}f(y)dy \dfrac{d}{dx}\int^{F(x|y)}_{-\infty}f(y)dy=\int^{\infty}_{-\infty}f(x|y)f(y)dy=f(x)?

A paper was published on today's ArXiv that questions the empirical basis of the acceleration of the expansion of the universe: Marginal evidence for cosmic acceleration from Type Ia supernovae . The authors are: Jeppe Trst Nielsen1, Alberto Guanti1, and Subir Sarkar1;2 (1Niels Bohr...

I'm trying to get a better understanding of marginal stability and the s domain in general. According to my textbook, a system that is marginally stable has poles that are conjugates of each other on the jω axis, and their magnitude are the resonant frequency for which if a sinusoid of that...

I have a set of two related queries relating to marginal pdfs: i.How to proceed finding the marginal pdfs of two independent gamma distributions (X1 and X2) with parameters (α1,β) and (α2,β) respectively, given the transformation: Y1=X1/(X1+X2) and Y2=X1+X2. I am using the following gamma...

The cost function of a firm is given by C(x) = 300x - 10x^2 - 1/3x^3. A) Find the Marginal Cost Function B) Average cost function C) The output at which marginal cost is equal to average cost.

Here is the question: I have posted a link there to this thread so the OP can view my work.

Homework Statement Your weekly cost to manufacture x bicycles and y tricycles is C(x,y)=20,000+60x+20y+50√(xy) a. What is marginal cost of manufacturing a bicycle. b. What is the marginal cost of manufacturing a tricycle. c. What is the marginal cost of manufacturing a bicycle at...

Given a plane with three points, (0,−1), (2,0), and (0,1) with x-axis and y-axis connecting three points to make a triangle. Suppose this triangle represents the support for a joint continuous probability density Pick one of the following: The marginal density f(y), defined as ∫f(x,y)dx...

Given a plane with three points, (0, -5), (10,0), and (0, 5) with x-axis and y-axis connecting three points to make a triangle. Suppose this triangle represents the support for a joint continuous probability density What can we say about the marginal density f_2(y)? Are they going to be...

Consider the function APL=\frac{\sqrt[4]{L}}{L}, where L is the number of workers. The company has just hired 8 workers. What is the marginal product of the labor?I know that if I had the total product I could differentiate it and get the marginal product, but it's the average product that is...

Let A be the set of possible states of the world, or possible preferences a person could have. Let G(A) be the set of "gambles" or "lotteries", i.e. the set of probability distributions over A. Then each person would have a preferred ordering of the states in A, as well as a preferred ordering...

Please see the attached image for my question. I don't understand how to compute the integral, is there some trick? I do believe that to find fx(x) I integrate the joint pdf, with respect to x with the bounds set as the range of Y. But this leaves me with a very complex integration Similarly for...

Homework Statement Homework Equations My professor gives us the following formula: [ tex ] F_j(t) = \int\limits_0^t exp\Big\{-\sum\limits_{j=1}^J \int\limits_0^u \lambda_j^{\#}(v)dv \Big\} \lambda_j^{\#}(u)du[ / tex ] where [ tex ]\lambda_j^{\#}(t) [ / tex ] are the cause-specific...

Homework Statement Given joint pdf: f(x,y) = (2/(x2(x-1)))(y-(2x-1)/(x-1)) x>1, y>1 find marginal pdf fx(x) Homework Equations fx(x) = ∫f(x,y)dy, 0, ∞ The Attempt at a Solution fx(x) = ∫(2/(x2(x-1)))(y-(2x-1)/(x-1)) dy, 1, ∞ = [-2y(x/(1-x))/x3],1,∞ = undefined. stuck here

Homework Statement Let the joint density of the material and labor cost of a project be modeled by fx,y(u,v) = 2v*e-v*(2+u) u,v ≥ 0 = 0 otherwise a) find marginal density of X and Y b) find E(Y)...

Homework Statement (X,Y) is uniformly distributed over the area T = {(x,y): 0 < x < 2, -x < 2y < 0} Find the marginal probability functions ie f_{x}(x) and f_{y}(y). The Attempt at a Solution The thing I'm having trouble with is that y depends on x. Am I supposed to rewrite the...

Hello, i have the following conditional distribution fXY(x,y)=2, of 0<x<1 and x<y<1 When i calculate the marginal distribution of y i don't know what interval of integration to choose. I made the graph of x<y<1 and the points(x,y) for x<y are above x=y on that graph but i don't know how to...

The annual demand q for bottles of wine from a vineyard when the bottles are priced at p dollars each satisfies the equation qe0.03p = 4000. The price is currently \$12 per bottle. Find the rate at which demand changes (with respect to time) if the price increases at a rate of \$1.20 per year.

Here is the question: Here is a link to the question: CALC. HELP! Related Problems!?!? - Yahoo! Answers I have posted a link there to this topic so the OP can find my response.

Homework Statement Let X and Y be random variables of the continuous type having the join p.d.f.: f(x,y) = 8xy, 0<=x<=y<=1 Find the marginal pdf's of X. Write your answer in terms of x. Find the marginal pdf's of X. Write your answer in terms of x. Homework Equations The...

Homework Statement Discrete random variables X and Y , whose values are positive integers, have the joint probability mass function pXY(x,y) = 2-x-y. Determine the marginal probability mass functions pX(x) and pY(y). Are X and Y independent? Determine E[X], E[Y], and E[XY]. Homework...

Homework Statement A point is chosen randomly in the interior of an ellipse: (x/a)^2 + (y/b)^2 = 1 Find the marginal densities of the X and Y coordinates of the points. Homework Equations NA The Attempt at a Solution So this ought to be uniformly distributed, thus the density function...

Homework Statement The joint probability density function of ##X## and ##Y## is given by $$f(x,y) = \frac{1}{8}(y^2 - x^2)e^{-y},\,\,\,\, x \in\,[-y,y]\,\,,y \in\,(0, \infty)$$ Compute the marginal densities of ##X## and ##Y##. The Attempt at a Solution I know the defintions are $$...

Homework Statement Hi all, I'm looking at the joint pdf F(x,y) = (8+xy^3)/64) for -1<x<1 and -2<y<2 (A plot of it is here: https://www.wolframalpha.com/input/?i=%288%2Bxy%5E3%29%2F64+x+from+-1+to+1%2C+y+from+-2+to+2 ...sorry about the ugly url) and trying to find the marginal PDFs for X and...

Hi all, I'm looking at the joint pdf F(x,y) = (8+xy^3)/64) for -1<x<1 and -2<y<2 (A plot of it is here: https://www.wolframalpha.com/input/?i=%288%2Bxy%5E3%29%2F64+x+from+-1+to+1%2C+y+from+-2+to+2 ...sorry about the ugly url) and trying to find the marginal PDFs for X and Y. I know I want to...

Homework Statement For a certain product, cost C and revenue R are implicitly given as follows, where x is the number of units sold (in hundreds) a) Find and interpret the marginal cost dC/dx at x=5 b) Find and interpret the marginal revenue dR/dx at x=5Homework Equations C2 = x2+100√x +50...

Homework Statement Suppose that X1 and X2 have the joint pmf f(x_{1},x_{2})=p^{2}q^{x_{2}},x_{1}=0,1,2,...,x_{2},x_{2}=0,1,2,... with 0<p<1,q=1-p Homework Equations The Attempt at a Solution I'm confused because the expression doesn't have x_1 in it. So usually, if I want to...

confused Andrew, Beth, and Cathy live in Lindhville. Andrew’s demand for bike paths, a public good, is given by Q = 12 – 2P. Beth’s demand is Q = 18 – P, and Cathy’s is Q = 8 – P/3. The marginal cost of building a bike path is MC = 21. The town government decides to use the following...

Homework Statement The random variables X and Y have a joint probability distribution of f_{XY}(x,y)= \frac{1}{2\pi \sigma _X \sigma _Y \sqrt{1-\rho ^2}} \exp \{ \left [ -\frac{1}{2(1-\rho ^2)} \right ] \left [ \left ( \frac{x-\mu _X}{\sigma _X} \right )^2 + \left ( \frac{y-\mu...

In trying to work out what Fermat may have conceived of as his proof, using the mathematics available at the time I have the following suggestion: Fermat's Last Theorem can be expressed the following way: There are no natural numbers A, B, C, N >1 for which a non-trivial solution of the...

Homework Statement Problem 2 Assume that the number Y of customers entering a store is a Poisson random variable with rate λ . Let X denote the number of these customers being a woman. The probability that a customer is a woman is denoted by p. Also, assume that all customers enter the...

Homework Statement Let f(x,y) = 24xy where x=[0,1], y=[0,1], x+y=[0,1] Find E[X] and E[Y] Homework Equations E[X] = the integral from neg. infinity to positive infinity of x * f_X(x) dx where f_X is the marginal density function of X. The Attempt at a Solution f_X is found by...

Suppose I have the marginal probability density functions of two random variables A and B, P(A), and P(B). Suppose I modeled P(A) and P(B) using a mixture model from some dataset D and obtained a closed form pdf for each. I am interested in finding their joint density function P(A and B) and...

Consider a set of n numbers, and let their arithmetic mean be X. Suppose a new number Y, is added to the set. Prove that the mean of the new set, with (n+1) members, is between X and Y. I've been trying to prove this the past few minutes, but I think I'm at a dead end. It's a problem that...

I had questions on 2 Problems in the Text: 1. The total cost C of producing x units of some item is a function of x. Economists use the term marginal cost for the rate of change of C with respect to x. Suppose that: C = 5x^2 + 15x + 200 What is the marginal cost when x = 15? Would this...

Hi.. Until very recently, I have what can be called a marginal interest in computers and even more so in math (mostly because any math I can do is limited to AS Level and despite being able to deal with abstractions in other disciplines, I seem not to have caught on the math front..I was also...

Hi, This is my first post in one of these forum; I hope someone can help me with this --thanks in advance for reading! I'm trying to find the joint probability distribution of two non-independent variables given only their marginal distributions. In fact, I'm interested in the joint...

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}...