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# Forum: Probability

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

1. ### 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)...

• Replies: 0
• Views: 30,323
09-30-2005, 09:44 AM
1. ### Adjusted odd ratio interpretation

Hi There, I have a question regarding adjusted ODD RATIO interpretation I am trying to interpret a table of results of logistic regression...

• Replies: 1
• Views: 8,692
06-11-2009, 08:09 AM
2. ### CDF of difference of chi squared random variables

Hi, I posted this question under "Probability Theory" and got no response. Maybe I'd have better luck here? I'm interested in obtaining a...

• Replies: 1
• Views: 8,659
BGM
11-10-2011, 03:50 PM
3. ### I need helpf with this one, for probability - binomial distribution

According to a recent study, 38% of all women will suffer a hip fracture because of osteoporosis by the age of 85. If six women aged 85 are randomly...

• Replies: 4
• Views: 8,654
06-01-2012, 12:04 PM
4. ### Joint Density f(X,Y) integration when there is no Y in the eqn

Hi I'm having difficulties with integration by parts when the main function of a joint distribution doesn't contain the Y. Here it is: Let X and Y...

• Replies: 24
• Views: 8,651
BGM
02-14-2011, 04:09 AM
5. ### quick question: probability of being dealt a royal flush?

if you have a standard deck of cards and are dealt 5 cards randomly, what are the chances of getting a royal flush? i feel like this is pretty...

• Replies: 5
• Views: 8,631
02-02-2012, 05:57 PM
6. ### Adding normal distribution - z-scores

Hi - I have a quick question. I understand that the sum of two normal distributions is a normal distribution. Now let's say I have the z-score...

• Replies: 5
• Views: 8,630
06-05-2012, 09:21 AM
7. ### Pizza toppings problem

Ok - first, let me state the questions, then what I did. Suppose that a pizza shop offers ten different toppings for its pizzas, and you select...

• Replies: 3
• Views: 8,619
02-01-2006, 11:43 AM
8. ### Buffon's Needle Experiment

This problem is quite interesting: A fine needle of length l is dropped at random on a board covered with parallel lines distance d apart where...

• Replies: 0
• Views: 8,610
10-04-2005, 02:08 PM
9. ### Probability for Zener pyshic card test

Hi, My Name is Mark Fennell, and I am a flash game developer. (My games are at www.markfennell.com/flash and www.blastone.com) Anyways, my next...

• Replies: 3
• Views: 8,564
01-20-2009, 09:01 PM
10. ### Biased Coin and Conditional Probability

Here's another question that I'm trying to work the kinks out of. Consider a biased coin with the probability of getting heads being p. The coin...

• Replies: 1
• Views: 8,560
10-04-2009, 06:53 PM
11. ### Conditional Probability

I need help with a couple of conditional probability questions: If a person is vaccinated properly, the probability of his/her getting a certain...

• Replies: 4
• Views: 8,531
11-20-2013, 10:57 PM
12. ### Show that Expectation does not exist ?

I've been stuck on this question for a few hours and would appreciate any help. Q. X is a random variable with mass function Px(x) =...

• Replies: 2
• Views: 8,526
BGM
04-20-2011, 11:38 PM
13. ### How to calculate probability on dice groups.

I'm a game designer studying the probability curves of various dice throwing mechanics. I know some basic statistics but it's been a while since I...

• Replies: 6
• Views: 8,521
BGM
12-23-2010, 02:39 PM

Eight tyres of different brands are ranked from 1 to 8 (best to worst) according to mileage performance. If four of these tyres are selected at...

• Replies: 2
• Views: 8,515
03-20-2006, 10:42 AM
15. ### Poisson Distribution(Homicide Deaths)

Hi, I have attempted the following question. Half I could solve, I need help to complete it. Question In one year, there were 116 homicide deaths...

• Replies: 1
• Views: 8,506
04-14-2009, 09:01 PM
16. ### Binomial Distribution help

Assume that a procedure yields a binomial distribution with a trial repeated n times. Use the binomial probability formula to find the probability of...

• Replies: 2
• Views: 8,504
BGM
12-12-2010, 02:03 PM
17. ### Finding data value corresponding to a probability

My apologies if this is in the wrong section first of all, probability seemed appropriate. Starting off with the question I'm trying to come up...

• Replies: 6
• Views: 8,412
03-20-2011, 06:47 PM
18. ### Median and Mean of Independent Random Variables

Hello, Here is the question: Let X_1,X_2, . . . ,X_n be random variables with the density \frac{1}{1+x^2} for x \in ({-\infty},{\infty}) ;...

• Replies: 5
• Views: 8,397
07-08-2012, 09:54 AM
19. ### Validity of setting constant to zero

Can anyone tell me the validity of setting the constant term to zero to make the other coefficients pass significance? I have been sent a multiple...

• Replies: 3
• Views: 8,389
05-13-2009, 05:32 PM
20. ### Variance of the sample variance

I am looking to compute the variance of the sample variance. I found a site that does this for the biased sample variance (i.e. 1/n rather than...

• Replies: 2
• Views: 8,325
10-25-2010, 10:39 AM
21. ### probability Homework help please

I have a stats probability problem for homework. It is a chart showing a survey of patients regarding satisfaction with care and type of surgery. ...

• Replies: 2
• Views: 8,317
10-22-2008, 07:05 AM
22. ### Thinking Fast and Slow - Probability question

In his book (Thinking Fast and Slow) Kahneman states: For example, if you believe that 3% of graduate students are enrolled in computer science (the...

• Replies: 17
• Views: 8,307
02-08-2012, 04:30 PM
23. ### Student Enrollment Probability

Hey everyone, back again with another problem giving me problems. A local university reports that 3% of their students take their general...

• Replies: 6
• Views: 8,303
02-27-2009, 07:44 PM
24. ### uniform distribution

A manager of a store reports that the time of a customer on the second floor must wait for the elevator has a uniform distribution ranging from 2 to...

• Replies: 5
• Views: 8,296
10-24-2005, 12:04 PM
25. ### linear combination of exponential distributions

I have an equation with linear combination of exponential distributions, i.e. sum (c_i * exp(a_i)) on the right hand side, and on the left hand...

• Replies: 2
• Views: 8,254
05-10-2011, 06:09 PM
26. ### Binomial Distribution Problem - How to interpret the given information

Your company is running an audit on the Sleaze Company. Because Sleaze has a bad habit of issuing incorrect invoices, the focus of your audit is on...

• Replies: 5
• Views: 8,231
10-04-2011, 01:58 PM
27. ### Logistic Distribution Question

I have two independent random variables each with a logistic distribution (not necessarily same mean and variance). How is the difference (or sum)...

• Replies: 6
• Views: 8,222
04-27-2010, 07:22 AM
28. ### Probability of exactly one?

Hello, I have a question that I am stuck on. Given: the probability of passing a Photography class is 75% and the probability of passing a...

• Replies: 9
• Views: 8,210
11-21-2008, 07:29 AM
29. ### Conditional covariance

X_i\sim Ber(\frac{1}{4}) and Y_i\sim Ber(\frac{3}{4}). Find Cov(\sum_{i=1}^{N} X_i,\sum_{i=1}^{N} Y_i) where P(N=k)=\frac{1}{2^k} for k=1,2,3,.... ...

• Replies: 5
• Views: 8,195
05-15-2011, 10:09 AM
30. ### Advantage of reducing process variation?

The question is, "What is the advantage of reducing process variation, thereby causing process control limits to be at a greater number of standard...

• Replies: 4
• Views: 8,193
03-08-2012, 02:30 PM
31. ### Appropriate Hypothesis

A company with a large fleet of cars hopes to keep gasoline costs down, and sets a goal of attaining a fleet average of at least 26 miles per gallon....

• Replies: 2
• Views: 8,187
06-07-2011, 10:26 PM
32. ### Expected value and variance of bootstrap estimate

Hi all! I have a question about bootstrapping. Let the variance estimate based on B bootstrap samples be \widehat{SE}^2_B =...

• Replies: 2
• Views: 8,141
04-19-2010, 06:59 AM
33. ### Joint probability distribution table

Helllo, I have this problem for an assignment: 1. It is known that box C has 3 blue balls, numbered from 1 to 3, and 2 red balls, numbered from 4...

• Replies: 1
• Views: 8,140
10-18-2010, 05:16 PM
34. ### Alternative to chi-squared test needed

Hi all. I need a goodness of fit test for a situation in which a chi-squared test isn't appropriate - where the sum of the expected values does...

• Replies: 5
• Views: 8,111
04-15-2011, 05:23 PM
35. ### Geometric Probability

Can someone help me with this problem and check my answer.. (I know its a long read but the questions are not hard) Mr. Nedrdly, the long time ap...

• Replies: 1
• Views: 8,095
01-12-2007, 07:30 PM
36. ### CDF problem

Problem - Let X be a random variable with c.d.f. F(x). Find the c.d.f. of aX + b first for a > 0, then for a < 0. (for a > 0) F(x) = P(X <= x) ...

• Replies: 8
• Views: 8,095
11-02-2010, 04:24 PM
37. ### Calculating Hazard Ratios

Hi there, I would like to calculate the hazard ratio (or deviation from the mean) for an 'event' My data has the dates of 'events' and I would...

• Replies: 4
• Views: 8,086
MrT
08-28-2013, 09:12 AM
38. ### The probability of seeing 13 minutes past the hour at least once every day?

Each day, there are 24 opportunities in a 24 hour period to see 13 minutes past the hour. There are 60 x 24 possible times that can be reported in...

• Replies: 28
• Views: 8,072
11-08-2014, 03:40 PM
39. ### Sampling Error Probability

Hello, This is my first time posting here, I stumbled upon this site when I was searching for information on the following problem which I...

• Replies: 3
• Views: 8,068
06-29-2009, 06:15 PM
40. ### Simple probablility question

A closet contains 8 pairs of shoes. If 4 shoes are randomly selected, what is the probability that there will be no complete pair? So i know that...

• Replies: 8
• Views: 8,067
06-08-2010, 05:53 PM
41. ### Difference between two Normal Distributions

I have a problem where I have two Normal distributions both with a standard deviation of 20 and a difference between the means of 17. I want to work...

• Replies: 0
• Views: 8,066
06-13-2006, 10:41 AM

There are three teams in a cross-country race. Team A has five runners, team B has six runners, and team C has seven runners. In how many ways can...

• Replies: 9
• Views: 8,049
09-16-2010, 07:06 PM
43. ### Freeman-Tukey transformation

Hi everyone. I am pooling proportions for meta-analysis. As part of this project I have been exploring variance stabilizing transformations for...

• Replies: 0
• Views: 8,039
03-31-2008, 12:12 AM
44. ### Probability, binominal distribution

A hotel manager knows that approximately 5 % of the reservations are so called “no-shows” – people who have made a reservation, but do not arrive...

• Replies: 6
• Views: 8,027
02-03-2010, 03:22 AM
45. ### Margin of Error/Sample Size...

I have another questions that I am not totally sure of the answer.... It has to do with the size of a sample. This is the question... Q: A...

• Replies: 1
• Views: 8,022
11-12-2005, 09:09 AM
46. ### Elevator probability question

This morning, when I walked into the elevator, I had this question in my mind. Five people walk into an elevator at Ground level. There are 17...

• Replies: 4
• Views: 8,009
04-18-2008, 02:27 PM
47. ### How do you find best probability density distribution for a data set?

How do you find the best probability density distribution that fits a particular data set? Is there any software that will take a data set and run...

• Replies: 2
• Views: 8,003
03-07-2012, 02:15 PM
48. ### How do I add percentages?

For instance, let's say a person is a truck driver and there's an: 80% chance of they smoke 40% chance of they are overweight 60% chance of they...

• Replies: 4
• Views: 7,996
05-03-2010, 11:15 AM
49. ### Homework Help with continuous probability distributions

Hi if anyone can help me on these two problems, i would really appreciate it. i'm looking at my notes and txtbook, but still don't understand it. ...

• Replies: 1
• Views: 7,980
BGM
10-19-2011, 11:52 PM
50. ### Not understanding Normal Distribution

I am having trouble wrapping my head around normal distributions and the revelance it has with statistics.--- Can someone help me to understand in...

• Replies: 3
• Views: 7,960
10-24-2005, 03:43 PM
51. ### Business Stats question...desperate for help

My professor has assigned this problem and I have no idea what else to try. I have tried binomial distributions and poisson. It is in a chapter on...

• Replies: 1
• Views: 7,941
02-16-2009, 09:44 PM
52. ### figuring out a cutoff value

:confused: Hello :confused: Since my teacher hasn't replied to any of my e-mails, I could use some help related to continuous probability...

• Replies: 1
• Views: 7,914
05-19-2006, 12:20 PM
53. ### Pooled Variance Distribution

Hi, I hope I am posting this in the correct forum. I have two populations and I've been taking samples from each population and calculating the...

• Replies: 3
• Views: 7,905
11-29-2010, 07:59 PM
54. ### Conditional expectation, normal distributions

I'm having some trouble with the following problem: Problem: Let X and Y be independent N(0,1) random variables. Determine E(X|X>Y) My...

• Replies: 4
• Views: 7,895
BGM
06-27-2013, 05:38 PM
55. ### Find the constant that makes f(x,y) a probability density function

Let X and Y have a joint density function given by f(x,y) =e^(-kX), 0<=X<inf, 0<=Y<=1, k is a constant, and 0 elsewhere Find the value...

• Replies: 12
• Views: 7,868
10-05-2011, 09:36 PM
56. ### Genotype probabilities

I'm having difficulty with this problem, although it seems easy. The possible genotypes of an organism are AA, Aa and aa (Aa and aA are...

• Replies: 1
• Views: 7,824
10-11-2010, 11:59 PM
57. ### Probability of combinations of events

Hello, I am trying to solve the following problem: We have a set of events and we know the probability of each event. We do not have values for...

• Replies: 2
• Views: 7,819
10-11-2010, 11:38 PM

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