1. S

    Problem with arguing about probability mass of general random variable

    (I'm not sure if this is the right sub-forum, but I didn't see a better fit.) I have a problem with an exercise in a machine learning text-book. Solving it doesn't require any knowledge of machine learning, though, just of advanced probability theory. It's a very simple exercise in principle...
  2. idontknow

    Equation with natural variable

    \lfloor n/1 \rfloor + \lfloor n/2 \rfloor +...+\lfloor n/(n-1) \rfloor =7\; , n-natural . To write it better : \sum_{j=1}^{n-1} \displaystyle \lfloor \frac{n}{j} \displaystyle \rfloor =7 \; ; n=? , Method Required !
  3. idontknow

    3 variable equations

    Solve for positive integers : x+y+z=xyz .:cool: Method required !
  4. W

    How to take this variable out of this equation?

    I'm working to develop a function in my embedded code for i2c initialization. I came up to this equation which is to calculate the speed of the i2c clock. But if I want to develop a function that takes a user popular numbers for speed then I have to change the shape of the equation to get...
  5. idontknow

    Equation with complex variable

    z=\ln x +i \pi x =0 . x=? , x\in \mathbb{R} .
  6. Chemist116

    Is the method to solve this single variable equation used correctly?

    The problem is as follows: A king decides to split an award between his three best archers after organizing an accuracy contest in his court. The first one gets $\frac{2}{5}$ parts of the total minus $\frac{1}{5}$ of a pound, the second gets $\frac{2}{5}$ of the rest minus $\frac{1}{5}$ of a...
  7. D

    Calculate probability of interval with a random variable?

    Hi! I have studied algebra and calculus mostly (Calculus 1), not so much probability. So my problem is that I have a random variable called r that can generate any number from 1 to 100 (1 and 100 are included, interval [1, 100]). I set up a condition that if r >= 1 and r <= 75 then generate a...
  8. A

    How can I calculate the joint probability for three variable?

    I am a student studying the joint probability density function with multi variables. I understand how to obtain a joint probability density function when two uniform distributions have the following joint distribution like below. The distribution $f_V$(v) can be determined based on the...
  9. S

    Function Of Discrete Random Variable

    Suppose you are playing a game that costs 8 dollars to play. You flip 10 coins and, for every head, you win 2 dollars. Whats the probability you lose money?
  10. T

    Hello Mathaholic, can you help me to create a formula with these variables

    If X is trading balance, Y% is max loss per trade and Z% is stop loss. For Example: X = $1000 trading balance Y= max loss per trade at 0.6% of trading balance Z = stop loss at -8% from entry point What would be the formula to calculate a position size of a single trade based on...
  11. J

    Distribution of a Monotonic Function of a Discrete Random Variable

    Suppose I have a discrete random variable $Y$ with PMF $f(y)$ and support $\lbrace 1, 2, ..., N \rbrace$. Suppose I define another discrete random variable $H=Floor(Log_2(Y))$. Floor is simply the function which returns the integer part of a value, so all decimal points are truncated...
  12. J

    Interpretation of Conditional Distribution of a Function of a Random Variable

    I know how to find the conditional distribution of two random variables, say X and Y, given their probability density function: f(Y | X=x) = f(x, y) / f(x) However, suppose I want to find the conditional distribution of a function of a random variable. For example: Does f(Y/(1-x) | X=x)...
  13. Z

    Expected Value of Discrete Random Variable

    Suppose A and B are discrete random variables. They have mean 0 and variance 1. Let C =max(A$^2$,B$^2$) Find: 1. E[Z] $\leq$ 2 2. p=cov(A,B). Prove that E[Z] $\leq$ 1-$\sqrt{1-p^2}$ I've done part 1, need help for part 2.
  14. L

    Need help figuring out an equation with a variable (?)

    It will quickly become painfully obvious that I am not a math person. I work with seniors and try to help give them an idea of how long their money will last once they go into a facility for care. I just want a simple, basic formula to give a senior an approximation of how long their money...
  15. J

    Moment generating function for a random variable described by a piecewise pdf

    Part e) is the problem in question here; I'm not exactly sure how to find the moment generating function, specifically when 1 <= y < 2. I know that M(t) = the integral from -infinity to infinity of e^(tx)*f(x)*dx, but do I simply use 2-y for f(x) on that interval? I'm not exactly sure, I think...
  16. H

    Variable radius of curvature in terms of sagitta

    How can I express a radius of an arc R in terms of its sagitta H assuming that: (a) the arc follows a locus of a circle with a variable radius, (b) arc length S is constant. I’m interested in the region where the included angle of the arc is between but not equal to 0° and 4°.
  17. S

    Expected value of a function of a discrete random variable

    I'm new here, so perhaps this is beyond the intended purpose of the board. But, that doesn't mean it's beyond its members. Here is the question: An insurance company sells a one-year automobile policy with a deductible of 2. The probability that the insured will incur a loss is 0.05. If there...
  18. N

    Random variable, graphs, prob. distribution

    Hello everyone. How can i solve this exercise? (select any variant of F) I cant understand how to solve it :(
  19. P

    Find the support of the density function of the random variable $X + Y$ .

    The support of a function $f(x)$ is defined to be the set $\{x : f(x) > 0\}$ . Suppose that $X$ and $Y$ are two continuous random variables with density functions $f_X(x)$ and $f_Y (y)$, respectively, and suppose that the supports of these density functions are the intervals $[a, b]$ and...
  20. D

    Definition of a random variable

    Hi guys Definition from book: A random variable $X$ is defined to be a numerically valued function of the elementary events $Ei$ what does it mean it plain english? I understand the numerical and the random aspect but how is it a function of events?