Variables Definition and 1000 Threads

I remember an argument, I think due to David Mermin, that refutes local hidden variables in a single measurement (as opposed to Bell's Inequality, which requires gathering statistics of many measurements). I know that's not a lot to go on, but I'm wondering if this rings a bell (no pun...

Homework Statement Let X and Y be rv's with joint pdf f(x,y) = 6(1-y) for 0≤x≤y≤1 and 0 elsewhere find Pr(X≤3/4, Y≤1/2) Homework Equations The Attempt at a Solution Ok I am having trouble with finding the right limits of integration for dependent variables. If we let the...

If I have a model with a categorical variable X1=0,1,2,3 and a continuous variable X2 and I have a regression model that includes an interaction between X1 and X2, then I decide I want to collapse X1 into an indicator variable where X1_new=0 if X=0 and X1_new=1 if X>=1, is my new model with an...

I have no idea how to solve this. All i can think of is that you need mass to solve the problem. Homework Statement A chain is lying flat on a table. It has no friction against the flat surface. You pull the chain to the edge of the table so that it from a resting state starts to slide down...

Homework Statement Match the function with the description of its gradient. Homework Equations f(x,y,z)=√(x^2+y^2+z^2) 1. constant, parallel to xy plane 2. constant, parallel to xz plane 3. constant, parallel to yz plane 4. radial, increasing in magnitude away from the origin 5. radial...

Can someone please help me solve the following using separation of variables: dy/dx = (xy + 3x -y-3)/(xy -4x+6y-24) so that the solution is written in the form: ((x+6)/(y+3))^7 =

Can someone please help me to calculate the following using separation of variables: dy/dx = x*(1 - y^2)^(1/2) to that the solution is in the form: y =

Homework Statement I am attempting to calculate a heat transfer across a medium with known material properties. I have the equation and all but one variable I have an exact answer for. I require the variance of my answer. Homework Equations I know ALL variables (ie numerical value) except...

Homework Statement Let ##H## be the parallelogram in ##\mathbb{R}^2## whose vertices are ##(1,1), (3,2), (4,5), (2,4).## Find the affine map ##T## which sense ##(0,0)## to ##(1,1), (1,0)## to ##(3,2), (0,1)## to ##(2,4)##. Show that ##J_T=5## (the Jacobian). Use ##T## to convert the integral...

Homework Statement Let X and Y be random losses with joint density function f(x,y) = e^-(x + y) for x > 0 and y > 0 and 0 elsewhere An insurance policy is written to reimburse X + Y: Calculate the probability that the reimbursement is less than 1. Homework Equations Have not...

When I have a function z = f(x, y), i. e., a function of various variables, the differential form of z is: dz = \frac{\partial f}{\partial x} dx + \frac{\partial f}{\partial y} dy or the derivative of z is: \frac{dz}{dt} = \frac{\partial f}{\partial x} \frac{dx}{dt} + \frac{\partial f}{\partial...

Homework Statement a and b are vectors in R^3 s.t. a=(1,7,-4) and b= -3j-4k 1. Find ||3a-3b|| (magnitude of 3a-3b) 2. Find unit vector u in direction of 3a-3b, write answer in form (u1,u2,u3) 3. Find vector of length 8 in direction of a (write answer in form "-") Homework Equations...

So I have had related questions over the past month, but I would like to ask this question to clarify my understanding. In thermodynamics you work with certain potentials, which are a function of the thermodynamic variables, i.e.: U(S,T,V,N,P) Now for U one has the identity: dU=...

How do I find a limit with two variables? Homework Statement lim(x->0)((1+ax)^(1/3)/(xln(1+x))-(arctan(bx)/(x^3)) http://www.wolframalpha.com/input/?i=lim%28x-%3E0%29%28%281%2Bax%29^%281%2F3%29%2F%28xln%281%2Bx%29%29-%28arctan%28bx%29%2F%28x^3%29%29 I understand that since the denominator...

Hello All! A recent problem has stuck with me, and I was hoping you could help me resolve it. Consider the following premise: Let us assume that X \sim \mathcal{U}(-3,3) (U is the continuous, uniform distribution). And let the transformation Y be applied thus: Y = \left\{ \begin{align*} X+1...

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

Homework Statement Hey. I need help simplifying and factoring a differential equation in terms of v and p (velocity(xdot) and position(x) respectively). I need the final answer to be in this form: a = ( )v + ( )p. This is so i can put the governing equation in a state-space and eventually use...

Homework Statement Solve the given differential equation subject to the indicated initial condition. (e^-y + 1)sinxdx=(1+cosx)d, y(0)=0Homework Equations Basically we have to use separation of varaibles to solve before using initial value condition.The Attempt at a Solution After separation...

1. I'll post here a simplified version of my problem Say you have a matrix A, and you want all its components to be functions, for example: A11 = Sin(a_n) A12 = Cos(a_n) A21 = Sin(b_n) A22 = Cos(b_n) And I want to be able to do this in mathematica so as to have the matrix A a...

Homework Statement Find the column of the matrix in Exercise 39 that can be deleted and yet have the remaining matrix columns span \mathbb{R}^4Homework Equations The matrix from problem 39 is \begin{bmatrix} 10 & -7 & 1 & 4 & 6 \\ -8 & 4 & -6 & -10 & -3 \\ -7 & 11 & -5 & -1 & -8 \\ 3 & -1 &...

It seems to me that for some thermodynamic variables it makes sense to talk of systems in contact with different values of these variables. An example is temperature. We can the problem of two systems in contact with different temperatures. However, I am not sure if this is the case for all...

I am studying Laplace's equation in my electrodynamics course (using griffiths intro to electrodynamics). I am watching a youtube video stepping through the separation of variables method for solving the PDE. It seems to be a common PDE that comes up repeatedly in physics (Helmholtz eqn, Poisson...

Let $\Omega=\{\omega_1,\omega_2,\omega_3\}$ an sample space, $P(\omega_1)=P(\omega_2)=P(\omega_3)=\dfrac{1}{3},$ and define $X,Y$ and $Z$ random variables, such that $X(\omega_1)=1, X(\omega_2)=2, X(\omega_3)=3$ $Y(\omega_1)=2, Y(\omega_2)=3, Y(\omega_3)=1$ $Z(\omega_1)=3, Z(\omega_2)=1...

Hello, I have two random variables X and Y that can take values of the kind (a,b) where a,b\in \{ 0,1,2,3 \}. Thus, the sample space has only 16 elements. I have, say, N observations for both X and Y, and I would like to know if there is some correlation between X and Y. - How is this...

How do you solve the system of equations e^{x_{1}+y_{1}}+e^{x_{1}+y_{2}}=a_{1} e^{x_{2}+y_{1}}+e^{x_{2}+y_{2}}=a_{2} e^{x_{1}+y_{1}}+e^{x_{2}+y_{1}}=b_{1} e^{x_{1}+y_{2}}+e^{x_{2}+y_{2}}=b_{2} x1, x2, y1, y2 are the variables for which I want to solve the equations, a1, a2, b1, b2 are...

Hi everyone, Homework Statement + Homework Equations + The Attempt at a Solution

Homework Statement Integrate the following over the set E. \int_E \frac{2x+y}{x+3y} dA Bounded by the lines: y = −x/3+1 y = −x/3+2/3 y = −2x y = −2x + 1 Homework Equations None. The Attempt at a Solution I can up to the same point everytime, but always get stuck on finding the new...

I would like some clarification as to the mathematical and physical definitions of the position variables in the wave function. I often see that it is treated as a variable independent of time; this is utilized in the separation of variables technique. However, the Schrodinger equation implies...

The solutions have came up with 5 equations, I'm not confused how they got those 5 equations but I don't understand how it was concluded that L = 0 and m = p = 1/√2.

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...

Hi, i was wondering if the following is valid: E[x/y] = E[x] / E[y], given that {x,y} are non-negative and independent random variables and E[.] stands for the expectation operator. Thanks

Homework Statement X is uniform [e,f] and Y is uniform [g,h] find the pdf of Z=X+Y Homework Equations f_z (t) = f_x (x) f_y (t-x) ie convolution The Attempt at a Solution Obviously the lower pound is e+g and the upper bound is f+h so it is a triangle from e+g to f+h...

I wonder what parts of statistics have specific terms existing for them - I see a relevant notion which would be relevant, but not sure if there is a term for it. If variable values can be ordered then it possesses a median. If the values can also be added then they also possesses an average. A...

Heeeeeeellllllllllllllooooooooooooo, I have a question about HTML and PHP: Firstly, I am using Apache2 and PHP5 (I think) and running it as a localhost. I created a simple HTML form that sends the variables via post to a PHP file; there are two variables with the names "nickname" and...

I don't get the point of equations of state since they seem to me to just indicate that we defined too many state variables. Why not just trim down our set of state variables and do away with the equations of state (i.e. for an ideal gas, just notice that P and V are sufficient to describe the...

Problem: Find all the positive integer solutions where x and y are odd numbers, to the equation: 17x+11y=1000 Attempt of solution: First attempt: With Diophantine equation have gotten the answers: x=2000 y=-3000 and the general solutions will be: x=2000-11k y=-3000+17k Now...

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

Hello, i m trying to evaluate the following: r*x - r*y ≤ g, where r,x,y are nonnegative random variables of different distribution families and g is a constant nonnegative value. Then, Pr[r*x - r*y ≤ g] = Pr[r*x ≤ g + r*y] = ∫ Fr x(g + r*y)*fr*y(y) dy, where F(.) and f(.) denote CDF and...

If the distribution of a sum of N iid random variables tends to the normal distribution as n tends to infinity, shouldn't the MGF of all random variables raised to the Nth power tend to the MGF of the normal distribution? I tried to do this with the sum of bernouli variables and...

Okay the question is, after just attaining an expression for a second-order Taylor series expansion of the Coulomb potential Vc about an arbitrary value r = a, call this *,. to use this to attain an expression for V(x1,x2,x3) with the values of a determined by the equillibrium values of x1 , x2...

Hello all, I am trying to find and draw the domain of this function: \[f(x,y)=\sqrt{ln(\frac{9}{x^{2}+y^{2}})}\] Somehow I find some technical difficulty with it. I have found 3 conditions: \[\ln \left ( \frac{9}{x^{2}-y^{2}} \right )\geq 0\] and \[\frac{9}{x^2-y^2}>0\] and \[x^2\neq...

Hi there, in a paper the author obtains the integral $$\int_{a}^{\infty} \frac {g(\lambda(r))}{r}\mathrm{d}r$$ which is claimed to be equivalent to $$\int_{a/A}^{1} \frac {g(\lambda(r))}{\lambda (\lambda^3-1)}\mathrm{d}\lambda$$ making use of the relationship (previously physically...

biology urgent need help? An experiment is set up to test whether a particular insect prefer a dark or a bright environment. A chamber with a gradient in light intensity from one end (dark) to the other (bright) has been made. The experimental hypothesis is: “There will be a large difference...

Homework Statement if a value has a variables that cancel out can it be considered a constant? looking to make an equation out of proportionality statements Homework Equations this is the equation that we are supposed to get: f=√((F)/(4∏2mr)) the 3 proportionality where f2=kF ...

The problem is as follows. Calculate the double integral of cos ((x-y)/(x+y)) dA over R, where R is the triangle bounded by the points (0,0), (2,2), and (2 + pi, 2 - pi). I understand that you have to set U = x-y and V = x+y. However, I am having a hard time finding the bounds on the...

Hi, http://www.dartmouth.edu/~chance/teaching_aids/books_articles/probability_book/Chapter7.pdf (see page 8, sum of two independent random variables). I don't understand why they had to go further into the limits, 1 < z < 2. Why do they have to do that? And also, where did they get it...

Hi guys! I have never used statistics in my life, so now I'm completely lost. I have only 3 variables - the year of the company founding (up to 1993, 1994-2004, 2005-now), the technological intensity of their products (that's either a, b, c or d) and the number of foreign markets (that's...

A random variable X is called sub-gaussian if P( |X| > t) \leq 2e^{-K t^2} for some constant K. Equivalently, the probability density p(x) is sub-gaussian if \int_{-t}^{t} p(x) dx \geq 1 - 2 e^{-Kt^2}. The challenge: Prove that the standard normal distribution (with mean 0 and...

Homework Statement The solid region W is bounded by the ellipsoid x^2/3 + y^2/5 + z^2/7 = 1. Find the triple integral ∫∫∫cos((35x^2 + 21y^2 + 15z^2)^(3/2))dV. Homework Equations Domain: x^2/3 + y^2/5 + z^2/7 = 1 Integral: ∫∫∫cos((35x^2 + 21y^2 + 15z^2)^(3/2))dV The Attempt at a...

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