Recent content by JamesF

  1. J

    Is My Formula for Conditional Expectation Correct?

    This result isn't in our book, but it is in my notes and I want to make sure it's correct. Please verify if you can. Homework Statement I have two I.I.D random variables. I want the conditional expectation of Y given Y is less than some other independent random variable Z. E(Y \...
  2. J

    How do I graph a summation using a TI 89?

    you could try RTFM. (hint: there's a MODE button on the 89. You're trying to change the graph MODE. hmmmm)
  3. J

    Rings and Homomorphism example

    can the ring be a division ring?
  4. J

    How do I graph a summation using a TI 89?

    Change the graphing mode to sequence.
  5. J

    Expected value of a third order statistic?

    alright I figured out my problem. I had it backwards. Our teacher uses (Y1) to denote the highest value of the 4 random variables, but the stuff I found on the web used Y1 to denote the LOWEST value. so f_{Y_3} = \frac{4!}{1! \cdot 2!} y \cdot (1-y)^2 \cdot 1 integrate to find the expected...
  6. J

    Expected value of a third order statistic?

    Hi all. I'm struggling with this HW question. I've searched through the textbook and on the web and have been unable to find a solution Homework Statement I've got 4 i.i.d. random variables, X1, X2, X3, X4. Uniformly distributed on [0,1] so the pdf = 1 and cdf F(x_i) = x_i Let Y3 = the third...
  7. J

    Abstract Algebra problem (related to Rings of Polynomails

    We'll I made it through another semester, but it seems that I am completely stuck on the last problem of the last homework assignment. I've made a little progress, but I'm really having trouble understanding the question. Perhaps someone on these forums will have some insight Homework...
  8. J

    Improving Numerical Approximations of Limits: A Sample Exam Question

    thanks for your reply. Let's see if I understand if f(h) = L - c_6 h^6 - c_9 h^9 - \cdots and f(\frac{h}{2}) = L - \frac{c_6 h^6}{64} - \frac{c_9 h^9}{512} what I'm trying to find is a_0, a_1 such that a_0 f(h) + a_1 f(\frac{h}{2}) \approx L . Is that right? I'm still somewhat...
  9. J

    Improving Numerical Approximations of Limits: A Sample Exam Question

    I'm having trouble with a sample exam question. I don't really understand the question, don't know what section of the book it relates to, and don't have any idea on how to solve it. I might be in trouble :) Can anyone provide any suggestions or guidance on how I might go about solving this...
  10. J

    Twice differentiable functions

    thank you very much Dick. You've been extremely helpful as always. I was able to get the answer.
  11. J

    Twice differentiable functions

    Hi all. Having a little trouble on this week's problem set. Perhaps one of you might be able to provide some insight. Homework Statement f:[a,b] \rightarrow \mathbb{R} is continuous and twice differentiable on (a,b). If f(a)=f(b)=0 and f(c) > 0 for some c \in (a,b) then \exists...
  12. J

    Compact Nested Sequences and Their Intersection

    Thanks for your help, Dick. I was able to get the solution. I have one more question on my current HW. Is a set A_n = [n, \infty) open or closed in \mathbb{R} ? I would think so, but it's unbounded.
  13. J

    Compact Nested Sequences and Their Intersection

    Hi everyone. I feel like I'm really close to the answer on this one, but just out of reach :) I hope someone can give me some pointers Homework Statement Let A1 \supseteq A2 \supseteq A3 \supseteq \ldots be a sequence of compact, nonempty subsets of a metric space (X, d). Show that...
  14. J

    Proving Convergence with Cauchy Sequence Method

    Hello all. I'm having trouble on the following homework problem. It seems like it should be easy, but I'm just now sure how to approach it Homework Statement Let (s_n) be a sequence st |s_{n+1} - s_n | < 2^{-n}, \forall n \in \mathbb{N} show that (s_n) converges The Attempt at a...
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