# statistics

1. ### I Is this weighted mean and standard deviation correct?

The expression I have found is this one. https://ibb.co/kqG24L3 I have been looking for information because I could not to realize what is the value that "alpha" has to have. If any of you do know what this alpha value is supposed to represent or if you have seen it before I would be really...
2. ### I Comparing theoretical calculations with experimental data

Dear users, The situation I have encountered is a simple statistical comparison of the experimental data, which accepted as correct, with the results obtained via six theoretical models. In the experimental data, there exist y values corresponding to x values and also the measurement errors of...
3. ### How do i answer this permutation question?

Question: A home security device with 10 buttons is disarmed when three different buttons are pushed in the proper sequence. (No button can be pushed twice.) If the correct code is forgotten, what is the probability of disarming this device? My attempt: 10!/(10-3)! =(...

21. ### Median vs. Second Quartile question

1. Homework Statement Lets say I have a list of numbers. income=[17000, 11000, 23000, 19999, 21000, 10000] I sort them income_sorted=[10000, 11000, 17000, 19999, 21000, 23000] Calculate med 2nd Quartile. 2. Homework Equations Median_formula = (n+1)/2 3. The Attempt at a Solution...
22. ### Conditional Expectations of 2 Variables

1. Homework Statement Suppose that the number of eggs laid by a certain insect has a Poisson distribution with mean $\lambda$. The probability that any one egg hatches is $p$. Assume that the eggs hatch independently of one another. Find the expected value of $Y$, the total number of eggs...
23. ### Expected bounds of a continuous bi-variate distribution

1. Homework Statement $-1\leq\alpha\leq 1$ $f(y_1,y_2)=[1-\alpha\{(1-2e^{-y_1})(1-2e^{-y_2})\}]e^{-y_1-y_2}, 0\leq y_1, 0\leq y_2$ and $0$ otherwise. Find $V(Y_1-Y_2)$. Within what limits would you expect $Y_1-Y_2$ to fall? 2. Homework Equations N/A 3. The Attempt at a...
24. ### Calculations using Standard Deviation and Mean

1. Homework Statement 2. Homework Equations Chebyshev's Theorem: The percentage of observations that are within k standard deviations of the mean is at least 100(1 - (1/k2))% Chebyshev's Theorem is applicable to ANY data set, whether skewed or symmetrical. Empirical Rule: For a...
25. ### Other Selecting a career with my BS in Applied Mathematics, BS in Physics and minor in Computer Science

This may be better suited in the academic forum, or possibly not even the normal type of question asked, but I was just judging based on other similar posts. I just graduated from college this past spring with a BS in Applied Mathematics and a BS in Physics, as well as a minor in computer...
26. ### Fortran Getting my method of bisection to output the correct value

I am trying to write a program that calculates the root of chi-square. I am not getting the correct answer and I honestly am at my wits end trying to figure it out. I know my simp_p() method is returning the correct value, but for some reason my root_chisq() method is not giving me the correct...
27. A

### Introduction Again

Hello! New here. Sort of. I have a major in math. I'd like to specialize in data science for my master's degree. This is my 2nd account here. I don't know how to delete the other one. Can anyone tell? Thanks.
28. ### Random walk - why is the STD equal sqrt(n)

typical random walk : one step forward or backward with equal probability and independence of each step , what is the expectation and Variance . so i define indicator variable xi ={1 or -1 with equal probabilty . E(xi) = 0 Var(xi) = 1 now define Sn as the sum of i=1,...,n each step is...
29. ### I Any database of results for the Michelson-Morley Experiment

Hello, I would be interested in a collection of experimental data for the Michelson-Morley Experiment . I would like to see if there would be many data available, and if a statistical analysis could be of some fun. Would you know some compilation of data? Thanks, Michel
30. ### Probability density function

1. Homework Statement Hello! I'm trying to understand how to solve the following type of problems. 1) Random variables x and y are independent and uniformly distributed on the interval [0; a]. Find probability density function of a random variable z=x-y. 2) Exponentially distributed...