Recent content by DanielJackins

  1. D

    Cartesian Product of two sets?

    Would it be like this? I think I've got it. http://i.imgur.com/TxF7bae.jpg
  2. D

    Cartesian Product of two sets?

    Homework Statement I need to answer a bunch of topological questions based on the cartesian product of two sets, but I'm not entirely sure how to graph them out. I have A = [1,2)U{3} and B = {1, (1/2), (1/3), ...}U[-2,-1). S = A x B, and I need the graph of S. Could anyone help me with...
  3. D

    Proving the memoryless property of the exponential distribution

    Thanks. Using that I was able to prove it. But why is what you said true?
  4. D

    Proving the memoryless property of the exponential distribution

    Given that a random variable X follows an Exponential Distribution with paramater β, how would you prove the memoryless property? That is, that P(X ≤ a + b|X > a) = P(X ≤ b) The only step I can really think of doing is rewriting the left side as [P((X ≤ a + b) ^ (X > a))]/P(X > a). Where...
  5. D

    Probability of something happening given the mean and the standard deviation.

    I'm doing a practice problem for my upcoming midterm and am stuck on a question. 3. The number of hurricanes that occur in the caribbean during hurricane season is a random variable, where the mean number of hurricanes occurring is 8, or E(X) = 8, with a standard deviation of 2.83. (a) Find...
  6. D

    Probability of rolling a sum of 6 before a 7 or 9

    Okay, that makes sense now (mostly). Wouldn't x and w be dependent as well?
  7. D

    Probability of rolling a sum of 6 before a 7 or 9

    Having a lot of trouble with this question. So first I tried making an equation, and I wrote that the probability = P(rolling a 6)+P(rolling a 6 and not a 7 on the first roll and not a 9 on the first roll) + P(rolling a 6 and not a 7 on the first roll and not a 9 on the first roll and not a 7...
  8. D

    Undetermined Coefficients problem

    Sorry, can you point out where I went wrong?
  9. D

    Undetermined Coefficients problem

    I thought I did? I said r^2+4r-5 = 0, which gave me r = 1 and r = -5, giving me the equation y = c1e^t+c2e^(-5t)
  10. D

    Undetermined Coefficients problem

    Homework Statement Find the unique solution to the differential equation y''+4y'−5y=−435sin(2t) satisfying the initial conditions y(0)=29 and y'(0)=47 The Attempt at a Solution So (I think) I found the correct general solution. I let y(t)=Acos(2t)+Bsin(2t) and eventually worked...
  11. D

    How Do You Solve a Trigonometric Differential Equation with Initial Conditions?

    But when I evaluate to find c1 and c2 I seem to get two different values for c1, and no value for c2? I'm not sure I understand
  12. D

    How Do You Solve a Trigonometric Differential Equation with Initial Conditions?

    Homework Statement Find the particular solution of the differential equation y''+36y=0 satisfying the conditions y(0)=−4 and y(pi/12)=3. Your answer should be a function of x. The Attempt at a Solution I think I know how to do this kind of question, and I can't see where I'm going...
  13. D

    Greatest common divisor question

    Oh got it, thanks for the help!
Back
Top