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Type: Posts; User: Rassis

by Rassis
Replies
8
Views
724

Great work.
2. ## Thread: sampling from defined distribution?

by Rassis
Replies
6
Views
458

### 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...
3. ## Thread: Cubic Spline Tutorial

by Rassis
Replies
27
Views
33,827

### 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.
4. ## Thread: Bookmakers betting book maths question

by Rassis
Replies
4
Views
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. ## Thread: [resolved] Easy question (Linear Functions)

by Rassis
Replies
3
Views
626

### 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;...
6. ## Thread: [RESOLVED] conditional formatting in excel

by Rassis
Replies
7
Views
599

### 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...
7. ## Thread: Probability problem the 2nd

by Rassis
Replies
2
Views
457

### 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...

by Rassis
Replies
2
Views
524

### Re: Probability problem

A Monte Carlo simulation model built in Excel yields approximately 0,73.
9. ## Thread: Probability problem the 2nd

by Rassis
Replies
2
Views
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...
10. ## Thread: Modelling of Graph

by Rassis
Replies
3
Views
404

### 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.
11. ## Thread: Another linear programming problem

by Rassis
Replies
2
Views
469

### 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...

by Rassis
Replies
10
Views
699

### Re: Linear Programming

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 =...

by Rassis
Replies
10
Views
699

### Re: Linear Programming

Here it is. Have a good time.

by Rassis
Replies
10
Views
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...

by Rassis
Replies
10
Views
699

### 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. ## Thread: Number of data points for statistical graph

by Rassis
Replies
4
Views
506

### 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
17. ## Thread: Making a variable the subject of formula

by Rassis
Replies
6
Views
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.
18. ## Thread: Area under a curve?? (Resolved)

by Rassis
Replies
6
Views
1,020

### 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...
19. ## Thread: Area under a curve?? (Resolved)

by Rassis
Replies
6
Views
1,020

### 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...

by Rassis
Replies
4
Views
681

### Re: Cumulative growth

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

Cheers

by Rassis
Replies
2
Views
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...

by Rassis
Replies
2
Views
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...
23. ## Thread: Random problems for fun?

by Rassis
Replies
6
Views
629

### 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...
24. ## Thread: Random problems for fun?

by Rassis
Replies
6
Views
629

### 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...
25. ## Thread: [RESOLVED] Generate Function values

by Rassis
Replies
8
Views
641

### 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.
26. ## Thread: [RESOLVED] Generate Function values

by Rassis
Replies
8
Views
641

### 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;...

by Rassis
Replies
3
Views
623

### 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...

by Rassis
Replies
3
Views
623

### 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...
29. ## Thread: Analysis of survey data - Pls help

by Rassis
Replies
1
Views
481

### 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 =...

by Rassis
Replies
36
Views
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.

by Rassis
Replies
10
Views
607

### Re: polynomial problem

Thanks Glaysher for the correction.

by Rassis
Replies
10
Views
607

### 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

by Rassis
Replies
3
Views
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.

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)...

by Rassis
Replies
2
Views
452

x = 2; y = 2

It was easy.

Regards,
36. ## Thread: misbehaving log-normal distribution in Excel

by Rassis
Replies
4
Views
1,353

### 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
37. ## Thread: misbehaving log-normal distribution in Excel

by Rassis
Replies
4
Views
1,353

### 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...
38. ## Thread: Integrating tan x

by Rassis
Replies
5
Views
786

### 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).
...
39. ## Thread: Differentiate log function

by Rassis
Replies
6
Views
820

### Re: Differentiate log function

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

The derivative you want is in position (20).

Regards
40. ## Thread: Help: Index Numbers & Inflation! :P

by Rassis
Replies
7
Views
712

### 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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