Forum: Probability

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

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...

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: ...

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...

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...

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...

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

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...

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...

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...

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...

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...

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

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...

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...

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.

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...

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....

: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...

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,...

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...

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

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

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...

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...

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....

x^n x to the power of n, x^2 is x squared nPr Permutation, nPr = n!/(n-r)! nCr Combination, nCr = n!/(r!(n-r)!) P(A|B)

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

An individuals’ heights are normally distributed with mean 70 and standard deviation 3 (inches). a) What proportion of the population is...

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...

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...

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...

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...

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...

Hey all, I've derived the expected value of the binomial distribution, but I can't seem to figure it out for the negative 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...

Hello all! Having a bit of problems here with making the table for a joint distribution: Question: 3 Fair coins are tossed. Let X = #of heads in...

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

Hi All, I'm going through revision questions, and I am stuck on this particular section all with similar questions. If somebody can give me a guide...

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

Hi- I have a function (ratio essentially) r= x / (1-x) I need some way of expressing the error of r ... I've experimentally measured x and...

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...

I'm confused about the following... Two people have their birthday on a specific day of the year. Are the odds 1:365 or 1:730 ? :confused: ...

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

can someone please explain how to do this problem? I am so confused! Assume the distribution of weights of US adults are normally distributed...

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...

those any one have this text. i have gone through all the questions in chapter 1 except for two prove questions. no 27 and 26 i am lost

Hello, My name is Chris and I would greatly appreciate some help concerning the folowing Probability problem. Suppose that the number of...

These are similar in principle to the binomial distribution, with one major exception - the hypergeometric probability is for situations where you...

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...

Hi If I roll a fair dice 10 times, what is the probability of getting at least two 6's? edit: Which method shall I use? Say, it's at least 3...

If I have uniform random variables X and Y in the range (a,b), how can I calculate joint probability distribution function p(y,x) for y...

I've decided to brush up on my statistics recently by jumping right in the middle of it, and I landed on the normal distribution. I have this...

The law of total expectation states that: E(X) = E and E = Eg(X)|Y)] 1) Now, is it correct to say that E(XY)=EXY|Y)] ? I don't think the above...