Test Definition and 1000 Threads

$\newcommand{\szdp}[1]{\!\left(#1\right)} \newcommand{\szdb}[1]{\!\left[#1\right]}$ Problem Statement: Let $S_1^2$ and $S_2^2$ denote, respectively, the variances of independent random samples of sizes $n$ and $m$ selected from normal distributions with means $\mu_1$ and $\mu_2$ and common...

Hi everyone, recently I was working out an elasto-plastic model to make some residual stress predictions: see it here. Recently I got some real tensile tests results from a lab, therefore I would like to extract a better stress-strain curve to plug into my elasto-plastic model using the...

Can you please help me Thank you in advance

Is there a " reasonable" way to test for the normality of ##\pi## , i .e., that every digit occurs with the same frequency? Someone suggested randomly sampling strings of size 20 and outputting the frequency. Then I guess we could average the frequencies among samples , use a chi-squared test...

I cannot figure it out which choice is correct Please help me Please! Thank you in advance

in order to solve a series, the root test is applied and I have this limit ## \lim_{n \rightarrow +\infty} \sqrt[n] {\left| {\frac {i^{\frac { n} {3}}} { \frac {2n} {3} +1}} \right| } ## I don't understand why at the second step the numerator becomes 1, cannot recall why it becomes 1, that is...

So I am having some difficulty expressing this series explicitly. I just tried finding some terms ##b_{0} = 5## I am assuming I am allowed to use that for ##b_{1}## for the series, even if the series begins at ##n=1##? With that assumption, I have ##b_{1} = -\frac {5}{4}## ##b_{2} = -...

For someone who has been vaccinated against Covid-19, will a subsequent Covid test show up as positve? If so, how is it possible to have a negative test after being vaccinated?

Use the algebraic tests to check for symmetry with respect to both axes and the origin. y = x^4 - x^2 + 3 Let y = - y -y = x^4 - x^2 + 3 y = (x^4 - x^2 + 3)/-1 y = -x^4 + x^2 - 3 Not symmetric with respect to the x-axis. Let x = -x y = (-x)^4 - (-x)^2 + 3 y = x^4 - x^2 + 3 Symmetric...

PUse the algebraic tests to check for symmetry with respect to both axes and the origin. x - y^2 = 0 Let x = -x -x - y^2 = 0 Not symmetric with respect to the y-axis. Let y = -y x - (-y)^2 = 0 x - y^2 = 0 Symmetric with respect to the x-axis.Let x = -x and y = -y -x - (-y)^2 = 0 -x -...

I recently had an incident in which a person visited my office and a few days later informed me he had tested positive for Covid. He had been healthy but took the test as required for any passenger boarding an airline. He later went for another test (the next day in fact) and that was negative...

The purpose of t test is to find how close the two means of the two samples given are; whereas the result of ##\chi^2## homogeneity test indicates the likeness of the two distributions of two populations (or maybe samples--I am not sure). Can anyone please tell me the differences between them...

I'm writing a Matlab script to calculate various properties in a shock tunnel. While this might sound silly but I am not well acquainted with the subject and have very few resources to compare. For a mach 6 test section is it reasonable to have a freestream pressure as low as 305 Pa?

I would like to find out please what is the preferred instrument to leak test very low levels of leaks of Americium, say in school sources. I mean an instrument which could measure leaks of 0.0005 microcuries. There are so many instruments. Some people say to measure the gamma emissions, others...

Dear friends i am using tensile test machine, tinius olsen 602 to conduct a tensile test for Glass-fiber composite. i am facing problem of using an extensometer from Epsilon (gage length is 25 mm). I have connected the extensometer to the tensile test machine(tinius olsen 602) through the...

Hi, I've been looking at Bells inequality test. To see if I understand it correctly I'd like to state it in my own words. Could you please let me know of I have it right? Thanks Michael We have 4 measurements, A,B,C,D Each measurement is True or False A is 0 degrees B is 45 degrees C is 25.5...

The first step is to group the data and make a table so I can get the observed frequency for each data interval. I did two different groupings (something like 150 - 160 , 160 - 170 , etc and the other is 150 - 170, 170 - 190, etc) and found out that the conclusion of the hypothesis is different...

From my understanding, Ames test is the test for mutation, not lethality at high enough concentration. Let me know if my understanding is wrong.

Hey! :giggle: Show for each sequence $(a_n)\subset (0, \infty)$ for which the sequence $\left (\frac{a_{n+1}}{a_n}\right )$ is bounded, that $\sqrt[n]{a_n}$ is also bounded and that $$\lim \sup \sqrt[n]{a_n}\leq \lim \sup \frac{a_{n+1}}{a_n}$$ I have done teh following: The sequence $\left...

In SPSS with the command sequence: Analysis / Dimension reduction / Factor / PRINT KMO Bartlett's sphericity test can be calculated. Now I read on: https://www.itl.nist.gov/div898/handbook/eda/section3/eda35a.htm that this test is a test for equal variances in dependent samples. My question...

I have an empirical frequency distribution as for example below: ##f_{2} = \, \, \, 21## ##f_{3} = 111## ##f_{4} = \, \, \, 24## The theoretical distribution is determined by two parameters. So for a chi-square goodness-of-fit test there are actually no degrees of freedom left. Yet the...

Here's the story: I did the 23&Me and it told me that I was about 90% X but then there was among the smaller %ages a Y = French Later, about a year later, I checked it again. The French ancestry had disappeared. There was still 90% X, but now I had a Y = Scandinavia. So, I ran the test again...

We can determinate if one number is prime with the modulo operation. https://www.researchgate.net/publication/346647223_Primality_Test_Formula

The Alternating series test has to be used to determine whether this series converges or diverges: \sum\limits_{n=1}^{\infty} (-1)^n\frac{\sqrt n}{2n+3} Here's what I have done: Let a_n = \frac{\sqrt n}{2n+3}. Therefore, a_{n+1} = \frac{\sqrt {n+1}}{2n+5} Now, for a_{n+1} to be less than or...

So far it seems to be limited to very few participants. It is SAE level 2 ("hands off"): The car drives itself but a human needs to watch it and needs to be able to take over at any time. Normally the phrase "self-driving" is only used for SAE levels 4 and 5 (you can sleep in the car, or you...

Can anybody point to an experiment that shows that the total entropy increases if two different gas mix at constant pressure and temperature, whereas if two volumes of identical gases mix the total entropy doesn't change?

Prof Wetterich has proposed that atoms are shrinking rather than the Universe is expanding. Here is a 2013 Nature News article describing his theory: https://www.nature.com/news/cosmologist-claims-universe-may-not-be-expanding-1.13379 Here is his 2013 paper "A Universe without expansion"...

Question: The national price of a good is distributed normally with mean £1.20, standard deviation 5p. Sample data is for price in London, determine whether there is sufficient evidence at 5% level to suggest that the mean price in London is different to the national mean. Standard deviation...

I would assume that because the samples are made of the same material they would fail at the same stress and so the same strain. However, the data shows that the sample with a greater cross-sectional area fails at a greater strain, and the two are roughly proportional. Does anyone know what...

The Journal of the American Medical Association (JAMA) today (7/28/2020) published an article on using presence of phospho-tau217 (p-tau217) in blood plasma to detect Alzheimers Disease. Over 80% specificity, and early results look like it could be predictive up to 20 years...

I worked for a relay company and the test equipment was left on 24 hours a day. One year they decided to shut down the company for 2 weeks so everyone got the same vacation. All the equipment was turned off. After the 2 weeks when everything was turned back on they had a tremendous number...

Is sunglasses test with UV flashlight correct or not?

Hello, I want to understand the difference between both goodness-of-fit tests, I would be glad if you could help me: Akaike Information criterion is defined as: ## AIC_i = - 2log( L_i ) + 2K_i ## Where ##L_i## is the likelihood function defined for distribution model ##i## . ##K_i## is the...

Electric potential energy at initial: Ee=kq1q2/r =(9 ×10 ^9×1.5×10^-6×(-5)×10^-6)/0.1 =-0.675J Electric potential energy at the closer point: Ee=kq1q2/r =(9 ×10^9×1.5×10^-6×(-5)×10^-6)/0.05 =-1.35J Δv=ΔEe/q =(-1.35+0.675)/1.5×10^-6 =4.5×10^5V or: Initial position...

Vehicle Mass : 3 tonnes Manufacturer's instruction is to test vehicle's parking brake effectiveness is to engage parking brake on 30.96 degrees slope. If it holds, it is effective. I do not have 30.96 degrees slope & I want to replicate the same test on flat ground. I was thinking of...

I read in this morning's newspaper, that we now have a test which was "found to be 100% accurate by experts". My personal crap detector pinged. (If you were not around in the 60's, just say I was sceptical.) Maybe they were not implying that the test IS 100% accurate, just that in their tests...

This UPS has been lying in the house for around seven years. We detached it from our desktop when it failed to provide backup. Six years back, I opened it up and found a swollen battery. At that point of time, I did not have any testing equipment, nor did I have any knowledge of electronics. So...

Hey! :o Let $Ax=b$ be a system of linear equations, where the number of equations is by one larger than the number of unknown variables, so the matrix $A$ is of full column rank. Why can the test for combatibility of equations use the criterion of the determinant $|A \ b|$ ? (Wondering)

Hi, I have a 25w 254nm bulb ozone free UVC bulb (draws about 19watts from my kil-a-wat). This was purchased from amazon, produced in China. This light definitely omits a funny smell, it pulls 19w, and the glow in the dark stickers are illuminated after my test (so I know it is omitting some...

I have 100 data. if I want to use data from 10 to 100 or from 20 to 100, which statistic should I use to test whether I can use data from 1 to 100 or 20 to 100 without significance?

Interestingly, If I neglect the ##(-1)^n## or ##(-1)^{n+1}## then apply preliminary test, I could find the limit. Whether the limit is not equal to zero, as in series number 1 and 2, then I can conclude the series is divergent. But, if the limit is equal to zero, as in series number 3, then I...

I want to use Q -test to truncate the data. But I have number of data 180 ( n = 180 ) How can i find Q critical value at 95 % Confidence ,When number of data equal to 180 ?

Is there a US engineering test to check academic level of a BE graduated in the Third World?

I know its because of tautomerism that they form an aldehyde group because of which they give the test but can all alpha hydroxy ketones give tollens test or only those in which hydroxy group is on the terminal carbon ??

The force on a test charge Q due to source charge q, depends on both their velocities in addition to several other quantities. For electrostatics, the source charge is at rest (its velocity is zero) but the test charge may be moving. Then how does Coulomb's Law accommodate for this velocity of...

SpaceX loves confusing numbering schemes, but so far we have seen five relevant test articles: Starhopper ("water tank") made a 150 m flight, Mk1 was the first full-scale prototype but got destroyed in a pressure test, Mk3=SN1 got destroyed in a pressure test, SN2 was a tank test only...

Hi PF! I'd like to test how fast my cpu clock speed is. Any recommendations with benchmarks so I can see just where I fit?

interesting: https://www.ncbi.nlm.nih.gov/pubmed/32133832?fbclid=IwAR3KtTRFTp9eb0aA-8ThVONEMGeGhecOnjMJtIblbClp8ufahx71HOFSWdg Objective: As the prevention and control of COVID-19continues to advance, the active nucleic acid test screening in the close contacts of the patients has been...

class PrimeTest { public static bool IsPrime(long n, int iteration = 5) { Random r = new Random(); long a = 0; long aPow = 0; for (int i = 0; i < iteration; i++) { a = r.Next(1, Convert.ToInt32(n - 1)); double x =...

Hi all, I have just started work experience at an engineering company in the design department. I've be tasked to develop a test rig, Similar to a charpy rig. Intended to measure the impact strength of materials. The design will consist of an A-frame structure with swing arm attached to the...