| Subject | Date Asked | Expert |
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| Sample size | 8/22/2007 | Ellis Godard |
Q: The company I work for has 2100 employees. We are interested in surveying a sample of our workforce ...
A: The size of the population is relatively insignificant in terms of statistical significance and ...
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| Alpha Levels | 8/20/2007 | Ellis Godard |
Q: I am having trouble understanding what the different outcomes/ advantages are when using a .01 ...
A: A .01 alpha level means that you leave open a 1% possibility of being wrong if you reject the null ...
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| which test should I use? | 8/18/2007 | Ellis Godard |
Q: Ellis, I am doing a research on the number of information sources used by people with different ...
A: if you combine the nominal measures into a total count of information sources used, that could be ...
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| 5-question exam | 8/17/2007 | Soroban |
Q: An exam is given to students that consists of 5 questions worth 20 points each. Suppose for an ...
A: Marissa! You're right . . . I spoke too quickly. With those probabilities, a student can expect to ...
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| probability over a time scale | 8/16/2007 | Ellis Godard |
Q: we've been arguing about this in my office at work for about an hour.... if the odds of winning a ...
A: if the odds are 1 in 700 each time, and you buy one chance each time, your odds are... 1 in 700 each ...
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| probability of poker hand | 7/30/2007 | Soroban |
Q: I need help with this problem: Suppose we're playing 5 card stud with honest players using a fair ...
A: Michelle! Your first statement is correct. The probability of getting EXACTLY one pair is ...
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| probability of poker hand | 7/30/2007 | Soroban |
Q: I need help with this problem: Suppose we're playing 5 card stud with honest players using a fair ...
A: Michelle1 How did you get that answer? (It's not correct.) There are 52 cards: 4 Aces and 48 ...
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| Probability - roll a given number of 1s out of 8 dice | 7/20/2007 | Soroban |
Q: I need to find the classic probability of rolling a 1 (or any number) out of 8 dice. I'm not looking ...
A: Sarah! >> I need to find the classic probability of rolling a 1 (or any number) out of 8 dice. >> ...
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| probability of getting cab drivers | 7/18/2007 | Soroban |
Q: If there are a pool of 1000 drivers at an airport each night (the same pool of cabbies drive each ...
A: Hailin! It's the second one: (1/1000)² The first driver can be ANY of them. (It doesn't ...
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| Probabilities | 7/18/2007 | Ellis Godard |
Q: I asked this question "If each month I have a 5% chance of selling my stock, and I can only sell it ...
A: My apologies. The option I clicked was "I believe that this is a homework question", which I used ...
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| combinations | 7/17/2007 | Soroban |
Q: I was wondering if calculating the number of different ways 24 numbers can be picked out of 75 is ...
A: Anna! What an interesting question! No, they are not the same. If we randomly pick 24 number ...
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| Ratio Vs. Continuous Scale | 7/16/2007 | Ellis Godard |
Q: I am still confused about Scales. Can you please tell me the difference between Ratio and Continuous ...
A: The difference is inconsequential for many forms of analysis, and so is a bit of a distraction. But ...
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| statistics | 7/16/2007 | Soroban |
Q: At Med University, the failure rate is 0.2 per year. There are 15 students registered in the ...
A: Shenlu! More of the Binomial Probability . . . >> At Med University, the failure rate is 0.2 per ...
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| statistics | 7/16/2007 | Soroban |
Q: Assume that airplane engines operate independently of each other and that at least half of the ...
A: Shenlu! I hope you are familiar with Binomial Probability . . . We have: P(fail) = 1/7, P(good) ...
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| combinations | 7/12/2007 | Soroban |
Q: How many 5 number combinations are there for 7,14,24,25,36,48,53
A: Carol! We are given 7 objects. We are to select 5 of them. (You said "combinations", so the order ...
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| probability | 7/11/2007 | Soroban |
Q: The student council is ordering pizza for their next meeting. There are 20 council members, 7 of ...
A: Shenlu! Let's call the vegetarians "V" and the non-vegetarians "M" (for Meat-eaters). a) There ...
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| probability | 7/10/2007 | Soroban |
Q: There are 8 opposite-sex married couples at a party. Two people are chosen at random to win a door ...
A: Shenlu! There are 16 people. There are: C(16,2) = 120 possible outcomes To choose two of ...
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| Statistics as used by the media | 7/10/2007 | Ellis Godard |
Q: Pre-election survey results are often used by the media. For example,they tell us that a survey by ...
A: You seem to be confusing the confidence level (95%) with the margin of error (+/- 2%), as though ...
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| When calculating odds | 7/9/2007 | Soroban |
Q: When calculating odds would you use Risk/(1-Risk) or Odds/(1+Odds) ?
A: Jannette! "Odds" are quite different from "Probability", as you probably know already. If I ...
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| Cards Disagreement | 7/8/2007 | Soroban |
Q: I deal out a single card in a regular deck to each of five card players. One person (A) received a ...
A: Mark! I hope I understood the problem . . . There are five players; each gets one card. Person ...
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| Statistics as used by the media | 7/8/2007 | Ellis Godard |
Q: Pre-election survey results are often used by the media. For example,they tell us that a survey by ...
A: It isn't exactly that particular ratios (such as 54-to-48) are "just as likely". If there was an ...
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| evaluation of rank order scaling (or rank ordered scale) data | 7/6/2007 | Ellis Godard |
Q: I have collected data where I've asked respondents to order their preferences for several different ...
A: There are several options. You could use cross-tabulations to look at the distribution of ...
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| How can I get the P value from a chi square | 7/5/2007 | Ellis Godard |
Q: Ellis, I am coding for a statistic project now. I have generated some chi square from the raw ...
A: There's not a formula, or at least not one that you probably want to deal with. You can, however, ...
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| probability | 6/30/2007 | Soroban |
Q: My question is about calculating the probability of rolling a sum of 7 using two six-sided dice. ...
A: Liam! You are wrong ... but please don't let that discourage you. You are Thinking ... and that ...
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| Lottery Odds for Multiple tickets | 6/27/2007 | Soroban |
Q: My coworker have to settle a dispute. Our Mega Ball lottery has a 1 in 175million chance to win. He ...
A: Mark! Sorry, your coworker is right. Consider a lottery with only 100 different numbers. If you ...
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| probablity | 6/20/2007 | Soroban |
Q: Show that f(-x)=1-f(x)
A: Beena! This is always given as a FACT. I've never been asked for a proof. I assume that those ...
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| probablity | 6/20/2007 | Soroban |
Q: The probablity of getting a royal flush when you deal out a five card hand is 1.54*10e-6.Suppose you ...
A: Lavanya! We are told that: P(Royal Flush) = 0.00000154 Then: P(not) = 0.9999846 Then we ...
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| replay soon..... | 6/18/2007 | Soroban |
Q: my questions are: Q 1.Three applicants are to be selected at random out of 4 boys and 6 girls. ...
A: Shani! Since the three questions are identical to those at the other site, I assumed you were ...
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| Probability | 6/17/2007 | Soroban |
Q: i. Three applicants are to be selected at random out of 4 boys and 6 girls. What is the probability ...
A: Ghulam! ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 1) Three applicants are to be ...
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| replay soon..... | 6/16/2007 | Soroban |
Q: my questions are: Q 1.Three applicants are to be selected at random out of 4 boys and 6 girls. ...
A: Shani! Questions #1 and #3 were answered at MathHelpForum. I'll explain #2. 2) Presume that in ...
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| Probability | 6/16/2007 | Soroban |
Q: This a problem I have on my statistics class and I don't know how to even begin breaking it down. ...
A: Ken! It's a sort of trick question . . . easier than you think. The first part is deliberately ...
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| Math help! | 6/4/2007 | Soroban |
Q: Two people share $76,500 in the ratio 13:21. Write the equation necessary to solve the problem to ...
A: Christina! I just solved this problem for someone else. You must be in the same class. If they ...
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| Permutations and Combinations | 6/3/2007 | Soroban |
Q: What is the difference between permutation and combination? Thank you
A: Dimitris! I will assume you know the formulas for Permutations and Combintions: P(n,r) = n! / ...
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| Causation | 5/30/2007 | Joe Engels |
Q: My problem is that I need to define causation and describe two factors that influence relationships ...
A: This is important to remeber, Correlation does not imply causation. Which means that although there ...
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| number combinations | 5/30/2007 | Ellis Godard |
Q: how many groups of 5 numbers can i get from the numbers 1 thru 36 ANSWER: i'm not sure what you ...
A: Basically the same question, basically the same answer - but you're missing the point of mycan the ...
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| Re: Some questions on standard deviation | 5/26/2007 | Joe Engels |
Q: Joe, Thanks for the speedy and helpful reply. I would like to ask you a follow-up question. >> ...
A: This was taken from the Emperical Rule, which says, if the data is normally distributed then about ...
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| probability witout replacement | 5/25/2007 | Soroban |
Q: Only one thousand tickets number 1 to 1000 are sold for a lottery with the first prize being a trip ...
A: Nikki! (a) There are 1000 possible tickets to be drawn. You have two tickets. Your probability of ...
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| Unequal variance.. maybe | 5/24/2007 | Joe Engels |
Q: I am looking at contamination concentrations in two different monitoring wells at several time ...
A: When using an F-test you are testing for equal variance. This would be approriate in this ...
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| Some questions on standard deviation | 5/23/2007 | Joe Engels |
Q: I need to know some things about standard deviation, coefficient of variation and variance. ...
A: Basically, for 1 standard deviation 68% of all lags will fall within 6.1247 seconds. That is what ...
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| advice on statistics used | 5/22/2007 | Ellis Godard |
Q: I'm using a pre and post questionnaire with 11 questions to see if my intervention changes people's ...
A: to control for those other variables, you'd want to do a regression equation. an 11-pt scale may be ...
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