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Type: Posts; User: Rassis

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  1. Re: [resolved] Probability of x within n attempts - two answers

    Great work.
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    Re: sampling from defined distribution?

    I don´t know how to do it in VB but it is quite easy to do it in MS-EXCEL. I think it won´t be difficult for you to translate the code in cell I15 in sheet "data and Results" into VB.

    To get new...
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    Re: Cubic Spline Tutorial

    VBAhack thanks for the excellent posts and job well done!

    Unfortunately I am not allowed by the administrator to rate your post as I have already done it the last time.
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    982

    Re: Bookmakers betting book maths question

    If horse A is a non-runner, then the total percentage before adjustment is: 33.33 + 4.76 + 4.76 + 4.76 + 4.76 = 52.37.

    Now adjust all the 5 figures in the following way:

    33.33 x 119.04/52.37 =...
  5. Re: Easy question

    Hi, wellcome to the forum,

    All you have to do is to apply the formula Y = 5 - X to your data, X being any value in the table.

    For instance:

    X = 1; Y = 5 - 1 = 4
    X = 2; Y = 5 - 2 = 3
    X = 3;...
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    Re: conditional formatting in excel

    See the attached Excel spreadsheet. Random numbers between 10 and 100 are input in cells B5 to G28. Cell I5 down to cell I28 yield the number of formatted cells in each row. They all match the same...
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    Re: Probability problem the 2nd

    The probability of failing one or more of the 4 subjects/semester in a time span of 1 year is 0,213.
    The probability of failing one or more of the 4 subjects/semester in a time span of 3 years is...
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    524

    Re: Probability problem

    A Monte Carlo simulation model built in Excel yields approximately 0,73.
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    457

    Re: Probability problem the 2nd

    Do you mean earning no credits at least once in any one of the 24 subjects (4 subjects/semester x 6 semesters) or no credits, coincidently, in all of the 8 subjects (4 subjects/semester x 2...
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    Re: Modelling of Graph

    Among a few others, this software can be the solution of your problem: http://www.palisade-europe.com/bestfit/
    It is very popular in simulation analysis.
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    Re: Another linear programming problem

    According to the Simplex Method Tool (http://people.hofstra.edu/faculty/Stefan_Waner/RealWorld/simplex.html)

    Minimize p = 0.01x + 0.021y + 0.015z subject to
    1x + 3y + 3z = 10
    1x + 2y + 2z = 8...
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    Re: Linear Programming

    I used your link. I entered:

    Maximize p = 24x + 20y subject to
    2x + 1.5y <= 9000
    x + y <= 5000
    x + 2y <= 8000
    x <= 5500
    y <= 3500

    And got the answer: Optimal Solution: p = 112000; x =...
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    699

    Re: Linear Programming

    Here it is. Have a good time.
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    699

    Re: Linear Programming

    I am sorry but the simplex algorithm is boring and too much time consuming. I left it apart since long. In my professional activities, I use Solver in Excel or What´s Best, Lingo or Lindo software...
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    Re: Linear Programming

    Objective function: max.Z = 24X + 20Y

    Constraints:

    Grade A: 2X + 1.5Y <= 9,000
    Grade B: X + 2Y >= 0
    Type 1: X + Y <= 5,000
    Type 2: X + 2Y <= 8,000
    0 <= X <= 5,500
    0 <= Y <= 3,500
  16. Re: Number of data points for statistical graph

    The answer to your question and any further questions you may have on stats can be found in this excellent e-book:

    http://www.statsoft.com/textbook/stathome.html
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    3,253

    Re: Making a variable the subject of formula

    Because you can´t get the equation into a closed form w = f(M,r,n,D), as VBAhack pointed out, I suggest you use Goal-seek in Excel.

    I attach an example.

    Hope it helps.
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    Re: Area under a curve?? (Resolved)

    I am glad that you found your way to the solution but, take into consideration what I said above about replacing the current empirical distribution by a theoretical one that fits the data available...
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    Re: Area under a curve??

    Considering the response times as a continuous variable (I didn’t quite understand why you gave only times rounded to units) the response is affirmative – yes it is a “question of finding the area...
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    Re: Cumulative growth

    years = [log(newpop/oldpop)]/[log(1+rate)]

    Cheers
  21. Thread: ...

    by Rassis
    Replies
    2
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    506

    Re: Farm management- Question

    Being C the number of ha to be planted with Corn and W with Wheat, we have:

    Objective function: max.P = 60.C+ 40.W

    Sbject to the constraints:

    9.C + 3.W <= 40,500
    3/4.C + 1.W <= 5,250
    C + W...
  22. Thread: ...

    by Rassis
    Replies
    2
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    535

    Re: Break- Even Points Question

    Hi,

    There are two breakeven points. They are: Making C = R, the following equation is obtained: x^2 - 100.x + 900 = 0. Solving for x, one gets x = 10 units and x = 90 units.

    The number of sold...
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    Re: Random problems for fun?

    The answer is, of course, correct. This question uses to be a little bit tricky when asked "in cold blood" because people tend to answer 125 Km/hour, or the arithmetic mean instead of the harmonic...
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    Re: Random problems for fun?

    That is too easy. Try this one:

    You move from a town to another one which is 300 Km away. You drive the first half of the way at a speed of 100 Km/hour and the second half at 150 Km/hour. What...
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    Re: [RESOLVED] Generate Function values

    After having seen the image and due to symmetry, x = -3.5955006 and y = -0.6713772 are also possible solutions.
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    Re: [RESOLVED] Generate Function values

    I know that this is not the type of answer that you are loking for, but even so, I would like to leave here a possible answer to the problem. The merit goes all to Solver of Excel.

    x = 3.5955006;...
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    Re: Statistician/Mathimagition needed.

    Longwolf,

    There is one more variable, which is important, that you are not accounting for: it is the number of sessions before going broke.

    I don’t know how to work out a formula that gives the...
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    Re: Statistician/Mathimagition needed.

    I don’t know anything about that specific game and its rules. All I know is that Risk is calculated multiplying the chance of something undesirable happens by its consequences (dollars, individuals...
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    Re: Analysis of survey data - Pls help

    Question 1:

    Mean = 3; SD = 1.8; n = 1,000

    P(x <= 2) = 0.28926 or 1,000 x 0.28926 = 289 visitors
    P(x > 5) = 0.13326 or 1,000 x 0.13326 = 133 visitors
    P(2 <= x <= 5) = 0.86674 - 0.28926 =...
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    26,145

    Re: LogNormal Distribution

    To integrate a lognormal function between 0 and x, you have to use the expression that is showed in post #10 above.
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    Re: polynomial problem

    Thanks Glaysher for the correction.
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    Re: polynomial problem

    If I understood it right, the answer is:

    Given: P(x)/(x-2) = 3 and P(x)/(x-3) = 2
    One gets: P(x)/[(x-2).(x-3)] = 1/[(x-2).(x-3)]/P(x) = 1/[(x-2)/P(x).(x-3)/P(x)] = 1/[(1/3).(1/2)] = 6
  33. Thread: Statistics

    by Rassis
    Replies
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    550

    Re: Statistics

    I corrected the result of the first question above: it must be 1,176 instead of 2,401 as I wrote the first place. I am so sorry.
  34. Thread: Statistics

    by Rassis
    Replies
    3
    Views
    550

    Re: Statistics

    Question 1:

    n = 35; p = 5/35; e = 0.02
    n0 = [Z(a/2)]^2.[p(1 – p)]/e^2 = 1.95996^2 x 5/35 x (1 – 5/35)/0.02^2 = 1,176

    Question 2:

    mean = 5%; stdev = 2%

    Using the expression Z = (p - mean)...
  35. Re: This is a challenging one for those who love some difficulty!

    x = 2; y = 2

    It was easy.

    Regards,
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    Re: misbehaving log-normal distribution in Excel

    I couldn´t agree more with Zaza´s words reagarding EXCEL. I regret having not stressed it before.

    Rui
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    Re: misbehaving log-normal distribution in Excel

    Ajmac,

    Despite the unfavourable report on EXCEL referred by RobDog888 ;) , I attach an EXCEL file which perhaps will bring some light to your problem (I posted it in a previous thread but here it...
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    Re: Integrating tan x

    I suggest that you use the Wolfram Integrator whenever you need a quick view of the result (just to confirm whether the calculus you performed is right or not).
    ...
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    Re: Differentiate log function

    Take a look at: http://mathworld.wolfram.com/Derivative.html

    The derivative you want is in position (20).

    Regards
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    Re: Help: Index Numbers & Inflation! :P

    Please see attached an example of what I mean. You can either adjust sales (or costs) of each year to conform year 1 prices or right the opposite: today´s prices. Today´s prices adjustment of...
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