probability

  1. A

    help!! I have a test and none of this makes sense.

    Hello! I have an exam on inferential statistics, etc and need serious help.
  2. G

    Probability Help

    Hello! Taking an introductory course on statistics in college. Confused about one question. It reads: The IRS reports that 15% of the tax returns where the adjusted gross income exceeded $1 million will be subject to computer audit. For a particular year, a CPA completed 16 returns where the...
  3. M

    conditional independence

    hello, I would like to ask the following: I have 3 random variables X , Y and Z. If I know that X is independent of Y given Z then does this imply that X is independent of Z? thanks !
  4. J

    calculating probability of disease according to age

    I'm making a program which, at one point, is supposed to estimate the probability of having a certain disease based on the patient's age. I'm going to feed the mean age at which the disease occurs, along with the standard deviation, into the program, but I can't figure out how to actually...
  5. W

    The Probabiliy of Making it

    I have 1,2,3,4,5,6,7,8,9,10,11,12 teams. Only 8/12 teams make it to the playoffs. What is the probability that 3,4,5,8,9,10 are part of the 8 teams that make it to the playoffs? Given each team has 1/12 chance of making it. I solved it like this, (8 choose 6) /(12 choose 8) = 0.056. Is this...
  6. S

    Simple but quite confusing Problem

    Hi all, I'm solving the problems in probability but, the question below looks simple but quite confusing to me. Regarding question 2-(c), any tips or advice would be appreciated to me. 2. Suppose that we have N balls numbered 1 to N. If we let Xi be the number on the ith drawn ball so...
  7. L

    Please help me start this question.

    Consider an experiment where we roll a single die once and let X represent the number of dots that appear on the top face of the die. Suppose that the die is not fair and that P(X=x)=x/k for x= 1,2,3,4,5,6. All I would like to know is what does the k in x/k mean in this question? How would I...
  8. M

    Compute time to sell (with 50% probability) at Price P from linear regression

    I think this is a very basic question (from a total stat newbie). I'm trying to understand a problem I was given (I'm not a statistics student). It's a multi-part problem having to do with car sales. In the first part, I ran a linear regression on car mileage/sales price data (price being the...
  9. P

    Tricky probability problem

    Hi, I was wondering if you could help me out with a problem I have: I need to work out the probability that someone will be able to complete a minimum of 10 hours of rehearsals in one week. The probability that this person is free each day is 60% on a weekday and 30% on the weekend. There are...
  10. S

    Multiple Inter-Correlated Binomial Events with only One Event Possible for Success

    Hi you’ll, I have a thought problem that might not have an easy/correct answer. It looks to be a Bayesian at first glance – and it might be – but because I am using some complicated machine-learning algorithms, and because of the nature of the problem, the water are muddy for me. I am just...
  11. K

    if z-value is a negative number, how can i calculate the Probability?

    Hello guys, :) I have an important question I want to ask. I have already searched the web and my statistics book but I can not find the answer :( I stumbled across this problem when preparing for my final from statistics and I can not figure out how we can get P=1 from a z-value=-10.6066...
  12. J

    Ploting Positions from Peak Over Thresold Series

    Hello. I have a little confusing with some aspect related to the Peak Over Thresold Series and differencing the methodology of analysis from that of the Maximum Annual Series. For example, for a daily series can one does this?: 1. Order the data (several years or a non-integer number of...
  13. E

    Comparing 2 groups of means ! shoud I use letters ?

    Hello, I hope everyone is doing well ! when comparing groups of means in a table, usually we express the differences in terms of letters next to each mean, like in the following example done by professor Gerard Dallal, which is dealing with four groups (A, B, C, D) My question now is : Can I...
  14. J

    Simple Probability Question

    OK, so I am wondering about something and am not good with probability, but maybe someone here has the answer You have a die with only 4 sides, with the numbers 1-4 written on the sides. You roll the die 5 times. What is the probability of the number 2 showing up: Once? Twice? Three times...
  15. E

    Soccer betting probability, risk and odds question - help

    Hello, Consider two different cases of soccer betting. 1) The first consists of 32 different sets of matches (each consisting of 5 matches with different odds of their own). Some of the individual matches (of 5 matches) in the sets can be the same with another set from time to time, but...
  16. T

    Help with interpreting data regarding religious Affiliation and aspirations to cheat

    An article is claiming that likelihood to cheat can be predicted by religious affiliation. I have provided some of their data on their sample of aspiring cheaters. I gathered data on religious affiliation in the United States. Given the following information, what can we conclude...
  17. U

    IP probability question

    hi guys. as you know, IP is a combination of 4 parts. every part is from 0-255, for example 234.32.135.7. now, my question is, what is the probability that two IPs will get the exact same first 3 parts. for example 1.2.3.234 and 1.2.3.121. is it just 256^3? and what is the chance that...
  18. M

    How to determine the accuracy of three combined tests

    Hypothetically, I have three tests that can determine if someone has cancer or doesn't have cancer. A True positive would indicate that the person doesn't have cancer. Below is a description of each test. Test 1: TP=.7 , FN = .3 , FP= .1 , TN = .9 , Accuracy = 80% Test 2: TP=.8 , FN = .2 , FP=...
  19. K

    A simple probability theory question, but the answer may not be simple.

    Hi, I have the following question. Suppose I draw a measure of 0<m<1 points uniformly without replacement from [0,1]. What is the probability that less than or equal to a measure of 0<k<m<1 points are drawn from the interval [i,1]? WLOG, suppose k<1-i. An example: a measure of 1/3 points...
  20. W

    2 Coops and Chickens problem

    Hi, I have a question as homework to solve, but although it's so easy (as everyone says) I am not still able to solve it. Could you please help me with that? We have two coops: in coop 1 there are 10 male and 5 female chickens. Coop 2 has 5 male and 10 female chickens. We randomly select...