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Forum: Probability

Probability course and homework discussion. Probability distributions. Probability theory, stochastic processes

  1. Arrow Sticky Thread Sticky: We only provide homework help to those who show effort

    Welcome to Talk Stats Forum. In order to keep homework help effective and efficient, we request all members to abide by these guidelines: 1)...

    Started by quark‎, 09-30-2005 10:44 AM
    • Replies: 0
    • Views: 11,524
    09-30-2005, 10:44 AM Go to last post
  1. probability with mean and standard deviation

    The local hardware store sells screws in 1lb bags. Because the screws aren't identical, the number of screws per bag, although distributed...

    Started by i need a brain‎, 06-04-2008 06:46 PM
    • Replies: 4
    • Views: 56,529
    03-06-2012, 05:20 PM Go to last post
  2. Significance Test: Ho & Ha

    Me again :) This is a long assingment I'm working on, and I have another question that I'm doubting my answer on.... This is the question: Q: ...

    Started by mackerbuddy‎, 11-13-2005 06:46 AM
    • Replies: 1
    • Views: 46,931
    11-13-2005, 09:40 AM Go to last post
  3. calculation of distance using Kullback–Leibler divergence

    Hi, Basically I'm from biology back ground. So it may be a basic question for you. I have two plots for example plot1: X - axis values: ...

    Started by asd123‎, 03-03-2011 05:39 AM
    • Replies: 2
    • Views: 33,934
    03-03-2011, 09:39 AM Go to last post
  4. need assistance

    I am taking a course in safety and now have one class left, but ran into a big problem. This class has statistics and I don't have a clue. The text...

    Started by double‎, 03-01-2006 11:35 AM
    • Replies: 5
    • Views: 33,646
    03-05-2006, 06:23 PM Go to last post
  5. Unhappy Calculating z value/mean and standard deviation

    Hi...have completed my assignment (and have come a long way with some helpful tips on this forum) but am stuck on one problem: In grading apples...

    Started by ShannonL‎, 11-05-2005 11:25 PM
    • Replies: 11
    • Views: 33,354
    01-07-2006, 10:22 PM Go to last post
  6. π-system and monotone class

    Assume P is a π-system (that is, P is closed under finite intersections) and M is monotone class (that is M is a non-empty collection of subsets of Ω...

    Started by hadiSanji‎, 12-17-2011 05:50 AM
    probability theory
    • Replies: 3
    • Views: 30,239
    12-17-2011, 10:54 AM Go to last post
  7. Var(X+Y+Z)

    What is the formula for the variance of 3 dependent variables? For 2 dependent variables, the formula is Var(X)+Var(Y)+2*Cov(X,Y) What is...

    Started by shrek‎, 07-08-2008 03:20 PM
    • Replies: 3
    • Views: 29,281
    07-08-2008, 04:18 PM Go to last post
  8. φ Distribution Table

    Hi, I'm currently looking for the φ distribution table, to calcuate marginal effects in a probit model. Unfortunatly there isn't one in my...

    Started by PaulDaniel‎, 04-15-2011 06:59 AM
    • Replies: 0
    • Views: 28,594
    04-15-2011, 06:59 AM Go to last post
  9. Finding Mean and Variance for X^2 Given Mean and Variance for X

    I am working on a question that has me stumped. X1, X2, ... Xn are normally distributed and independent. Each has a mean of 0 and variance sigma^2....

    Started by math_guy314‎, 11-05-2010 06:56 PM
    • Replies: 4
    • Views: 25,558
    11-08-2010, 06:47 PM Go to last post
  10. Probability Problem

    Pls help...........:wave: My problem exercise goes like this - An employee of the records office at a certain school currently has 10 forms on...

    Started by leo‎, 04-10-2008 09:31 AM
    5 Pages
    1 2 3 ... 5
    • Replies: 74
    • Views: 25,296
    06-04-2008, 08:00 PM Go to last post
  11. Binomial Probabilities

    These kinds of questions can be answered using the binomial probability distribution: 1. If I flip a coin 20 times, what is the probability of...

    Started by JohnM‎, 11-01-2005 02:50 PM
    • Replies: 0
    • Views: 25,018
    11-01-2005, 02:50 PM Go to last post
  12. Express E[X-μ]^4 in terms of....

    X is a random variable with moments E, E, E. Suppose var(X)= σ^2, skewness is given as S=/(σ^3). Express the right side of the following as in...

    Started by alias‎, 10-16-2011 11:52 PM
    • Replies: 0
    • Views: 22,767
    10-16-2011, 11:52 PM Go to last post
  13. Μarginal Distributions of f(x,y)

    f(x,y) = e^(-x), 0<=x<inf, 0<=y<=1 To find the marginal PDFs here is what I did so far: Marginal Distribution of x: f(x) = integral...

    Started by alias‎, 10-16-2011 07:28 AM
    • Replies: 2
    • Views: 21,979
    10-16-2011, 01:42 PM Go to last post
  14. E[MSE] simple linear regression

    Hi All- I am trying to figure out how to prove that MSE = SSE/n-2 is an unbiased estimator of sigma^2 in simple linear regression. I have that...

    Started by B_Miner‎, 10-01-2009 08:42 PM
    sigma^2, unbiased estimator
    • Replies: 14
    • Views: 20,982
    02-02-2013, 03:44 AM Go to last post
  15. I still need help please

    Ok, so I am still working on this freaking problem. Can someone help me please. It states that the scenario is normally distributed with a mean price...

    Started by BestNurse‎, 12-12-2009 08:42 PM
    • Replies: 12
    • Views: 20,530
    12-14-2009, 09:10 PM Go to last post
  16. The Probability of a Flush

    Hiya :) Im back for some more assistance.... Q: THE PROBABILITY OF A FLUSH A poker player holds a flush when all 5 cards in the hand belong to...

    Started by mackerbuddy‎, 11-14-2005 03:10 AM
    • Replies: 1
    • Views: 20,124
    11-14-2005, 09:45 AM Go to last post
  17. Probability in my exam

    Here is the scenario for my practice exam: "You have been hired by a firm which produces customised engineering machinery to provide some...

    Started by newbiestats‎, 11-13-2011 09:10 PM
    2 Pages
    1 2
    • Replies: 17
    • Views: 19,614
    05-30-2012, 02:34 AM Go to last post
  18. Expected Value of Exponential Distribution

    I've almost completed this problem, but I'm stuck on the last part. The first two parts that I've already shown are also given: a) For a whole...

    Started by moberle‎, 05-23-2007 05:27 PM
    • Replies: 1
    • Views: 19,346
    07-03-2007, 02:24 PM Go to last post
  19. Z-scores for probability in tails

    I haven't done any stats in years and now I am in a course for my grad program and I am so lost. My teacher is very confusing and I am trying my best...

    Started by rmbr2‎, 10-02-2008 02:18 PM
    • Replies: 3
    • Views: 18,981
    10-16-2008, 07:45 AM Go to last post
  20. What is the meaning of kurtosis?

    I found in Wikipedia that kurtosis is measurement of peakiness of the famous bell curve. If kurtosis is more than 3, it is kind of peaky, if kurtosis...

    Started by insight‎, 12-04-2007 05:30 AM
    • Replies: 10
    • Views: 18,853
    11-09-2011, 12:39 PM Go to last post
  21. MLE of a Gamma Distribution

    Hello everyone, I'm having quite some trouble with a question about the maximum likelihood estimator of a gamma distribution. The question is as...

    Started by Halfpixel‎, 11-26-2008 04:44 AM
    • Replies: 2
    • Views: 17,688
    11-26-2008, 01:24 PM Go to last post
  22. Standard Deviation from Percentiles and Mean

    Hello to all and thank you in advance for the help with this. I am working with a lognormal distribution and am given Percentiles - P10, P50, P90,...

    Started by rpmc‎, 06-08-2009 06:07 AM
    • Replies: 7
    • Views: 17,595
    12-23-2010, 02:14 PM Go to last post
  23. Lightbulb mann whitney test or Kolmogorov smirnov test?

    I'm working with non parametric methods to compare two samples and detect diferences between them. I used the mann-whitney test and obtained, for all...

    Started by Marga‎, 11-02-2006 06:46 AM
    2 Pages
    1 2
    • Replies: 23
    • Views: 16,472
    05-09-2010, 03:28 PM Go to last post
  24. M.g.f for Poisson distribution

    Hello, I am having trouble understanding the maths between E(e^{tx}) where I get a summation from 0 to \infty and the m.g.f for Poisson...

    Started by Trillian‎, 01-07-2011 07:26 AM
    mgf, poisson distribution, probability
    • Replies: 2
    • Views: 15,996
    01-07-2011, 01:55 PM Go to last post
  25. Can't understand some probability symbols.

    For two events, A and B, P(A) =1/2, P(B) =1/3, and P(A �� B) =1/4. Find P(B | A). The symbol where is shows a box here is an upsidedown U. Does...

    Started by jsundsmo‎, 06-16-2007 03:58 PM
    • Replies: 2
    • Views: 15,939
    06-17-2007, 02:00 AM Go to last post
  26. Question Help with finding indicated probability

    I have worked on this problem now for the whole entire day, and still don't understand what I am doing wrong. Can someone help me? The problem...

    Started by teneclady201‎, 07-10-2008 06:40 PM
    • Replies: 4
    • Views: 15,678
    07-13-2008, 07:04 PM Go to last post
  27. P-value from test statistic

    I'm given a test-statistic of 2.4 in one of those H0 type problem with a 0.05 significance level. In the z-table, if you look up 2.4, it says 0.0082....

    Started by robbiesqp‎, 12-11-2009 07:02 PM
    • Replies: 7
    • Views: 15,595
    03-18-2013, 02:26 PM Go to last post
  28. Removing an outlier DECREASES correlation??

    Here's my data. Note the "outlier" X LN(X) Y 4 1.386294361 0.107543212 6 1.791759469 3.289563593 7 1.945910149 2.058949066...

    Started by MrGibbage‎, 04-19-2010 02:38 PM
    2 Pages
    1 2
    • Replies: 15
    • Views: 15,539
    04-24-2010, 08:17 PM Go to last post
  29. Help! I’m baffled with a probability problem…..

    Hi, Newby here. I am hoping someone on here can assist with a probability question that’s troubling me. I have three ‘events’, in each event...

    Started by RobD‎, 01-09-2012 09:32 AM
    • Replies: 4
    • Views: 15,360
    01-09-2012, 11:39 AM Go to last post
  30. Geometric Distribution

    A geometric Distribution is a discrete probability distribution of a random variable x that satisifies: 1. A trial is repeated unitl a success...

    Started by galactus‎, 09-14-2006 06:48 PM
    • Replies: 0
    • Views: 15,284
    09-14-2006, 06:48 PM Go to last post
  31. Standard Normal Variable Z ... I do not understand

    :confused: Hi, This is not a homework question as I have the answer, just trying to figure out the method; I have a "Normal Distribution...

    Started by thedealer‎, 04-23-2006 03:25 PM
    • Replies: 2
    • Views: 14,434
    04-23-2006, 03:33 PM Go to last post
  32. probability of one random variable being greater than another

    I took statistics many moons ago, and remember performing these calculations, but for the life of me I can't remember what this process is called, or...

    Started by manzell‎, 03-07-2008 04:19 PM
    • Replies: 3
    • Views: 14,146
    04-22-2012, 01:38 PM Go to last post
  33. Sum of Poisson Distribution

    Hi everyone. Let X and Y be independent, with X~Poi(lambda) and Y~Poi(mu). Put Z = X + Y as their sum. Find the distribution X | Z = z.

    Started by woody198403‎, 08-18-2009 08:07 AM
    • Replies: 8
    • Views: 13,806
    02-13-2012, 07:50 PM Go to last post
  34. α = 0.05 vs p-value?

    So I've got a couple questions on my stats homework as follows: E. Canis infection is a tick-bone disease of dogs that is sometimes contracted by...

    Started by ryant‎, 09-29-2012 08:09 PM
    • Replies: 4
    • Views: 13,367
    09-30-2012, 05:51 AM Go to last post
  35. Doesn't "At least" mean greater than

    Thank you for taking the time to read my question :) I was given a question that reads: We would like to test whether the percentage of students...

    Started by ealeql‎, 09-26-2010 06:31 PM
    • Replies: 7
    • Views: 13,187
    09-27-2010, 11:35 AM Go to last post
  36. Permutations with Duplicates

    I have been trying to find information about calculating permutations that include multiple duplicate items, but have only found programming source...

    Started by Peelman‎, 10-18-2006 04:38 AM
    • Replies: 10
    • Views: 12,849
    10-30-2006, 03:34 PM Go to last post
  37. Maximum of a set of independent normal random variables

    Consider a set of random variables X_1, X_2, X_3, \ldots, X_n with unit varience but different means: \mu_1, \mu_2, \mu_3, \ldots, \mu_n . What...

    Started by mightymergz‎, 07-08-2010 03:50 PM
    2 Pages
    1 2
    • Replies: 20
    • Views: 12,528
    07-12-2010, 04:45 PM Go to last post
  38. Help about Isserlis’ theorem

    The Isserlis theorem states that if is a zero mean multivariate normal random vector, then : E = EE + EE + EE Now, in the case x,y,z,t are...

    Started by DejanM‎, 01-30-2012 12:38 PM
    • Replies: 0
    • Views: 12,466
    01-30-2012, 12:38 PM Go to last post
  39. Creating a joint probability table

    I need help figuring out how to create this joint probability table 43 million people in the United States go without health insurance. Sample...

    Started by elementarystat‎, 09-03-2009 03:17 PM
    • Replies: 3
    • Views: 11,243
    09-03-2009, 10:58 PM Go to last post
  40. Probability on a Multiple Choice exam

    Hello, I am not very good at this type of stuff. I thought up something and I was wondering if someone can look over it and tell me if my...

    Started by Paradox‎, 11-27-2010 04:01 PM
    2 Pages
    1 2
    • Replies: 18
    • Views: 11,178
    12-25-2011, 07:07 AM Go to last post
  41. Joint distribution, find P(X^2 + Y^2 <=1)

    I am trying to teach myself (without a tutor) some degree level Statistics. I think I've answered parts a-c of this question, but would like...

    Started by NicolaR‎, 01-16-2009 03:49 PM
    • Replies: 6
    • Views: 11,092
    01-17-2009, 02:42 PM Go to last post
  42. Combine Normal Distributions

    How do you combine multiple normal distributions with different standard deviations and means, to produce one representative normal distribution? ...

    Started by x46949‎, 05-01-2011 04:23 PM
    • Replies: 12
    • Views: 11,071
    01-26-2013, 12:51 AM Go to last post
  43. Find E(X) and VAR (X)

    Question is: There is one error in one of five blocks of program. To find the error, we test three randomly selected blocks. Let X be the number of...

    Started by smske‎, 01-15-2012 08:21 AM
    • Replies: 8
    • Views: 10,937
    01-15-2012, 03:26 PM Go to last post
  44. Equation for the Standard Normal Curve

    Does anybody know what the equation is for the standard normal curve? In my statistics class, we use a chart to find areas under the curve given...

    Started by dogginboggin‎, 04-15-2010 09:40 PM
    • Replies: 6
    • Views: 10,906
    04-16-2010, 05:52 PM Go to last post
  45. Unhappy Conditional Probability - Exam

    Someone can help me please, I need to understand them for my exam on Monday in next week. Today is Saturday.....Thanks a lot..... USING AND...

    Started by begacon‎, 07-28-2007 08:10 PM
    • Replies: 1
    • Views: 10,877
    07-29-2007, 08:05 PM Go to last post
  46. Product Normal Distribution

    Hi, Summing normal distributions is nice and easy, providing another normal distribution. But multiplying gives the Product Normal Distribution....

    Started by BigBugBuzzz‎, 01-20-2012 10:51 AM
    productnormaldist
    • Replies: 6
    • Views: 10,854
    01-20-2012, 12:54 PM Go to last post
  47. Uniform Probability Distribution

    The driving distance for the top 100 golfers on the PGA tour is between 284.7and 310.6 yards (Golfweek, March 29, 2003). Assume that the driving...

    Started by USMstudent85‎, 04-11-2011 10:51 AM
    • Replies: 5
    • Views: 10,833
    04-11-2011, 02:53 PM Go to last post
  48. Calculating probability of multiple events

    This is my first post so I hope I can get my question across reasonably intelligently. I have calculated the probability of an event occurring for...

    Started by Bear47‎, 11-18-2008 10:12 AM
    • Replies: 3
    • Views: 10,038
    11-26-2008, 05:24 AM Go to last post
  49. conditional binomial is a poisson distribution

    Hi, I'm fighting with this problem for a while. There is something important I'm missing So the problem goes like this X~Poisson(lambda) and Y|X=k...

    Started by exuberant‎, 12-24-2010 09:28 AM
    • Replies: 7
    • Views: 10,026
    06-11-2013, 09:59 AM Go to last post
  50. Question Discrete Probability Distributions - Shoot me now!

    I spent three hours at a basketball tournament trying to figure these out. Please help. Using the Poisson Probability Distribution I have the...

    Started by Parillamaster‎, 02-13-2006 09:08 AM
    • Replies: 2
    • Views: 9,723
    02-13-2006, 09:58 AM Go to last post
  51. http://en.wikipedia.org/wiki/27_Club

    There does seem to be a causal relationship between occupation and death, but why at 27? Does it mean anything?

    Started by Outlier‎, 07-23-2011 06:48 PM
    • Replies: 11
    • Views: 9,381
    07-29-2011, 10:20 AM Go to last post
  52. variance of binomial distribution

    The variance of a binomial distribution for which n = 100 and p = 0.20 is this is a practice problem for a test im taking next week. But i don't...

    Started by laneswilets‎, 02-23-2009 08:18 PM
    • Replies: 1
    • Views: 9,361
    02-23-2009, 09:46 PM Go to last post
  53. Figure out if there is any statistical significance

    Hi - I have some data on the internal temperature of cooked meat. The meat patty is a failure if the temperature obtained is below a certain...

    Started by mulamootil‎, 05-19-2010 08:13 PM
    • Replies: 8
    • Views: 8,977
    06-10-2010, 02:27 PM Go to last post
  54. probability of failure in a multi-component system

    I want to calculate the failure rate of a system that has multiple independent points of failure. If any one of these intermediate points fail then...

    Started by sbarefoo‎, 01-15-2010 08:44 AM
    • Replies: 2
    • Views: 8,971
    01-19-2010, 10:09 AM Go to last post
  55. Normal Distribution times constant

    I can't seem to find anything about this on the web. If I have a random variable distributed Normally: x ~ Normal(mean,variance) is the...

    Started by BigBugBuzzz‎, 09-30-2012 10:45 AM
    normal distribution
    • Replies: 3
    • Views: 8,632
    09-30-2012, 11:17 AM Go to last post
  56. find the expected value of continuous random vaiable

    Hi, To find the expected value of a continous random variable I normally integrate the pdf multiplied by the random variable over the range of the...

    Started by PeterVincent‎, 11-17-2009 04:13 PM
    • Replies: 10
    • Views: 8,565
    11-20-2009, 07:05 AM Go to last post
  57. Poisson distribution

    The Poisson Distribution is often used as a model for the number of events occuring within a specific time period. The Poisson probability mass...

    Started by quark‎, 11-17-2005 12:25 PM
    • Replies: 0
    • Views: 8,510
    11-17-2005, 12:25 PM Go to last post
  58. Exponential (θ ) distribution question

    Xsub1 and Xsub2 are independent Exponential ( θ ), θ >0, random variables. Let S= Xsub1 +Xsub2 Write the PDF of S stating any standard...

    Started by april_gsu2007‎, 11-08-2012 10:58 AM
    • Replies: 1
    • Views: 8,482
    11-08-2012, 11:41 AM Go to last post
  59. probability of consumption

    could someone let me know what i'm doing wrong? A study of the amount of time it takes a mechanic to rebuild the transmission for a 1992 Chevrolet...

    Started by rzum‎, 06-08-2007 03:13 PM
    • Replies: 4
    • Views: 8,396
    06-13-2007, 12:06 PM Go to last post
  60. Minimum of 2 Random Variables question

    R(1) and R(2) are 2 independent random variables with same density function f(x) = x*(e^(-.5 * x^2)) for x >= 0. Find the density of Y = min{R(1),...

    Started by StatStudent3‎, 11-04-2010 06:27 PM
    • Replies: 7
    • Views: 8,391
    11-06-2010, 12:13 AM Go to last post

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