Mean Definition and 1000 Threads

What does it mean that "acid is produced from ____" by bacteria? I've identified a bacteria (specifically stephococcus thermophilis) and am using Bergey’s Manual® of Systematic Bacteriology to learn more about it. The manual states S. Thermophilis produces acid from glucose, but not from...

what does it mean to just have σx and not σx/σy for instance?

What does living in exponential times mean?

Homework Statement It is in some notes that I found online in an attempt to understand something else that I need to know for a math course. Homework Equations f : ℕ → ℕ The Attempt at a Solution It seems to mean that a function of some natural number will equal some other...

I already know the definition: http://en.wikipedia.org/wiki/Orthogonal_functions But what does it mean intuitively, analytically, or in terms of graphs?

Homework Statement Calculate the mean velocity (um) for turbulent velocity distribution in a pipe. Homework Equations um = Q/A u = umax(y/R)1/7 (Gives velocity at a specified point in cross section of the pipe. R = pipe diameter. y = distance from boundary layer. umax = distance at...

Just need someone to tell me if I'm doing this right. If I have accelerated a particle in which the mean free path is 50nm and I need the collision to be 5eV would this be correct in determining the required electric field strength? 5/.00000005 = 100MV/m

Homework Statement Use the mean value theorem to show that \frac{b^3-a^3}{b-a} = \sum_{j=1}^{n}d_j^2 (x_j - x_{j-1}) \text{where} x_{j-1} < d_j < x_j . Homework Equations The mean value theorem states that if f is continuous on [a,b] and differentiable on (a,b) then there exists a c in...

Hi, Please see the attached Excel file. The list shows the old and new values of a set of variables. I am trying to understand what is the best way – average or median - to describe the change the values of the set. I want to describe the true central tendency of the change. 1. I...

Homework Statement Question ∫ secx^2 dx from 0 to ∏ I get tanx and evaluate it using limits lim tan(pi) - lim(tan(0)) I get 0 for both. What does it mean. Homework Equations The Attempt at a Solution The integral doesn't converge? I know it doesn't but what does 0 mean...

what does normality means, and how does it relate to molar concentration ?

If X is a locally compact Haussorff space, then the set of continuous functions of compact support form a normal vector space C_c(X) with the supremum norm, and the completion of this space is the space C_0(X) of functions vanishing at infinity, i.e. the space of functions f such that f can be...

For example my textbook reads if G(V, E) is a pseudograph then \sum\limits_{v \in V} deg(v) = 2|E|

Hello everyone. My understanding of a dipole moment is it defines the strength of various dipole interactions, eg the common example of torque in an electric field. My confusion stems from the fact that the magnitude of the dipole moment is proportional to the charge separation. In many...

f(x)=f(x)={█(2/(√2π) e^(〖-x〗^2/2)@0 otherwise)┤for 0<x<∞ Find the mean and variance of X The hint says, compute E(X) directly and then compute E(X2) by comparing that integral with the integral representing the variance of a variable that is N (0, 1)

Homework Statement Suppose that f(0)=-3 and f'(x)<=5 for all values of x. The the largest value of f(2) is A)7 B)-7 C)13 D)8Homework Equations The Attempt at a Solution The problem can be easily solved using the mean value theorem but solving it in a different way doesn't give the right answer...

Hi, everyone what is fertile free fuel ?

What does it mean when someone says that a book is dry ?Does the book lack explanation?or is the book boring? is it pejorative?

Hello physicsforums. What causes noise in electrical cables and/or transformers and/or electrical stations ? By noise I mean mechanical sound waves like bzzzzzzzz, not signal noise. And what is the proper way to search in google for this, I could not find a wikipedia article on this.

Consider a data matrix, X, with zero empirical mean. What is zero empirical mean? Could someone please give me an example of such matrix?

There's been an earthquake of about 4.7 on I don't know which scale less than 50 km away from where I live. I filled a questionnaire and there was the word askew in it, so I asked google what it means and... well try yourself. Put askew in google. :smile:

Hey guys... The part I DON'T understand clearly is the following part that is in BOLD "Science is more than a body of knowledge It's a way of thinking A way of skeptically interrogating the universe If we are not able to ask skeptical questions To be skeptical of those in authority...

Let xij be the ith independently drawn observation (i=1,...,N) on the jth random variable (j=1,...,K). These observations can be arranged into N column vectors, each with K entries, with the K ×1 column vector giving the ith observations of all variables being denoted xi (i=1,...,N). I have...

In the definition of an integral what does the astrix (*) mean above the x_i? I got confused in class today because the prof used an astrix but just to mean the equation we had been talking about. Also, I sometimes see the top of the sigma being n-1 instead of n. I guess it doesn't really...

This is what I understand. I can be wrong though. Please let me my conceptions are wrong. If by ''space'', you mean ''distance between two objects'' then the answer should be ''yes.'' Because since the distance between two distant objects in the universe is actually increasing, it should mean...

Homework Statement People drink on average, 78L of beer per year with a standard deviation of 25L. at least what percentage of people would drink between 20 and 136L per year? The Attempt at a Solution I found the z-scores of both and they came up to be +/- 2.32. Compared these values to the...

Attached is a copy of p181 of Strauss Partial Differential Equation. This is part of proof of Mean Value Property using Green's 1st identity: \int_Dv\nabla u+\nabla v\cdot\nabla u \;dV=\oint_A v\frac {\partial u}{\partial r}dA Let ##v=1## and let ##u(r,\theta,\phi)## be a harmonic function ie...

Does this just mean...matrices Homework Statement What does this mean ##βv## but pretend that the angle beta is lower case. This is how my book wrote it. Homework Equations The Attempt at a Solution

So when there is a dot above the equation it means with respect to time. What does it mean if there are two on the top or one on the side?

What do they mean that energy is "quantized"? I am SICK of hearing that "energy comes in packets". I understand what they are saying, but I don't comprehend it, or understand the intuition behind it. Someone PLEASE clear this up for me. Obviously, I speak English, and I understand the words...

Dear all, Can Torque max. be used instead of Power max. in the bmep equation?-(as shown on attached pic) The name of the equation seems to suggest it is only for Brake Power but hopefully i am wrong. Also, when I do a calculation for bmep for max. Brake Power and max. Torque, the bmep...

X (n by 1) follows a multivariate normal distribution, i.e., X ~ N(mu, Sigma). mu is n by 1, Sigma is n by n. What is E(X|X_{sub}=A)? where the index 'sub' (m by 1) is a subset of {1,2,..,n}, A is m by 1, 1 <= m < n.

Hi all, For finding average we take the sum of sequence numbers and divide by the number of elements. Why for variance this changes to number of elements minus 1. -Devanand T

Science fiction in my opinion means something scientific that isn't real (at the moment). Looking through history, star trek ect a lot of science fiction there has become a reality. I'm interested in hearing from people who teach / research physics if there was ever a time when something was...

Hello all, I have a couple of questions. First, about the mean value theorem for integrals. I don't get it. The theorem say that if f(x) is continuous in [a,b] then there exist a point c in [a,b] such that \[\int_{a}^{b}f(x)dx=f(c)\cdot (b-a)\] Now, I understand what it means (I think), but...

The curve C is defined parametrically by x = 4t - t^2 and y = 1 - e^-t where 0≤t<2 . Show that the mean value of d^2 y / dx^2 with respect to x over the interval 0≤x≤7/4 is (4e^(-1/2) - 3)/ 21 . I've figured out d^2 y/dx^2 as ((t-1)e^-t)/(4(2-t)^3) . Any idea how to do the the other part ?

I'm trying to come up with a good definition for model: X is modeled means x exists at time 1 and point 1 and has direction y, then it will exist at time 2 and point 2. Of course there are different types of modeling, for example, sometimes particles decay into other particles. Let me...

What is the sample mean of the following matrix?

Hi; According to Wiki the minus sign is a unary operator (a negator). Calculations are done right even if the minus sign is considered to be a (-1) multiplier. How to explain, for instance, -(a+b)=-a+-b if the sign is considered an operator? Thanks...

Hi all, I'm having trouble finding a certain generalization of the mean value theorem for integrals. I think my conjecture is true, but I haven't been able to prove it - so maybe it isn't. Is the following true? If F: U \subset \mathbb{R}^{n+1} \rightarrow W \subset \mathbb{R}^{n}...

We are all familiar with E=MC2, although I don't know how that formula relates to the big bang. In any case, I suspect I don't have the math to understand it and it would probably take several pages to define it. Everyone is familiar with F=MA. What most people don't know is that if you...

Hi all, I'm trying to calculate the M.A.P.E. using the accuracy() function in SDMtools. I have an output of 10.69. I'm not sure if this is 10.69% or 1069% as previously in a different model I had gotten an output of 0.34. If anyone is familiar with this, I would appreciate any help...

Homework Statement Showing all your working, calculate the arithmetic mean and standard deviation of the number of days lost. Table shows man days lost to sickness.. Days lost: 1-3 4-6 7-9 10-12 13-15 Frequency 8 7 10 9 6 Homework Equations...

Let X(bar)[sample mean] be the average of a sample of 16 independent normal random variables with mean 0 and variance 1. Determine c such that P(|X(bar)| < c) = 0.5 Ok here's the problem, I know this is SUPPOSED to be a simple computation but for one reason or another little ol' fooliosh...

1. Homework Statement a) Calculate the theoretical diameter of pipe, nominal pipe diameter and mean velocity of nominal pipe diameter. Maximum velocity = 1.8m/s Q(vol. flow rate) = 0.01M^3-1 b) Find the Reynolds number for the process and then the head loss due to friction, state any...

I'm reading Georgi Shilov's Linear Algebra and at the bottom of page 10 is has an equation $$a_{ij}=\lambda b_i+\mu c_i +\ldots +\tau ?_i$$ Where the ? is there is a symbol that I don't know. It looks like a curly lowercase f (like an integral symbol with a short stroke through the top part). It...

what does position entangled mean (physically)? The below is an attempt to understand position entanglement. It may require a lot of corrections and modifications. Look forward to your responses. A photon (A) would have a probability distribution, so would it's entangled twin/photon (B). The...

Hi! I do have this problem - Consider that for a set of values, I do have a Poisson distribution with mean value <m> - Now, I need to gather another set of dataset, which I should vary the mean value by 5% - My question is, how can I translate each one of these new values to sigma deviations...

I'm trying to make a MATLAB plot with two types of data, i.e. temperature and air flow rate. Since the temperature and air flow rate are on different scales I wanted two y-scales and since there are quite some data sets, I wanted to make the two air flow rates bold. I tried this, but it doesn't...

What does the word "action" mean in quantum physics? Hi everybody, I was reading about the application range of quantum mechanics. I found the effects of quantum mechanics are negligible where the action is on the order of the Planck constant. But, What does the word "action" mean? Thanks