Standard Definition and 1000 Threads

Homework Statement the question asks you to calculate the standard derivation for the mean distance of an electron from the nucleus. you are given the mean distance (<r>), and the probability density Homework Equations delta r = sqrt (<r^2> - <r>^2) <r> = 3.a/2 The Attempt at a...

Suppose that I can sample from some unknown continuous distribution. I know that the draws are iid, but the distribution itself is unknown. However, I know that the true distribution is one of two, either f(x|H) and f(x|L) with common support. I form the likelihood ratio...

Homework Statement Sally, Bob and Charlie each measure the period of the same pendulum to determine the acceleration of gravity, g. The lab instructions say that you should determine the period by timing the time of 100 swings (complete cycles) of the pendulum. Sally is the first to do the...

Hey, so I am teaching myself the C language to get a head start for a class I have to take later and am a little bit confused about something. I understand that if you call a function from within your int main, the variables you pass are actually copies of the originals and when the program...

Does anyone share the same strange feeling I have about the Standard Model? The feeling that it had almost failed… So, let me present you Standard Model: 3 generations, 2 types of particles (quarks and leptons), dividing into 2 subtypes (upper/lower, lepton/neutrino), giving 12 fermions, or...

Homework Statement Students measured an object 5 times, and got the results 11,25 cm, 11,20 cm, 11,22 cm, 11,18 cm i 11,25 cm. The height of this object is: A. h = (11,22 ± 0,03) cm B. h = (11,22 ± 0,04) cm C. h = (11,25 ± 0,07) cm D. h = (11,25 ± 0,03) cm Homework Equations Standard...

Why is it that change in enthalpy (h=e + pv) depends upon pressure as they say, we should measure at standard pressure, while pv=nrt so no matter da presure nrt is the same the product p by change in volume is constant so accordin 2 me we should specify only da temperature change...

How to compare the topology on R generated by the subbasis S={[x,y)|x,y are rational}U{(x,y]|x,y rational} to the discrete topology on R?

We've been watching this development taking shape ever since the tentative Gambini Pullin papers about it in 2006. It represents a fundamentally new way to address the problem of interpreting Quantum Mechanics. One person who worked on this back in 2006, with Gambini and Pullin, used to post...

Homework Statement Homework Statement Hello everyone! I have been having trouble with cumulative frequency graphs in excel for some time now. I wonder how you make the "bell graph" or cumulative frequency graphs or standard deviation graphs in microsoft excel. I have excel for mac. I...

D. When evaluating a mixed type expression (e.g. a + b) if either operand is a floating type, which of the following conversions or promotions may occur i. int is converted to float ii. float is promoted to double iii. double is promoted to long double iv. int is promoted to unsigned int...

Homework Statement the problem states solve for n. nP4 = 8(nP4) Homework Equations no relevant equat. i can think of? The Attempt at a Solution my attempt at this was nP4 = 8(nP3) idk what i tried to do, but i tried to get it in standard form i guess: n!/ (n-4) = 8(n!)/(n-3) it...

Hello everyone, Can anyone please help me to find where I can purchase the DIN 2999 standard? Regards Huygen

"Higgsless" Standard model I realize we haven't been able to see the signal for a Higgs boson directly yet, but I have heard there is plenty of indirect evidence for the Higgs (in that it is needed in the model to match experimental results). My question is essentially: are all forms of this...

--- Found solution. Nvm.

In a lot of compilations of standard integrals (my Calculus book does this, Wikipedia does this), a lot of the integrals of trigonometric functions have an absolute value in their solution which seems out of place to me. For example, take the integral \int dx \cot{x}. My Calculus book says...

Hi, I have a question about standard errors in the context of this problem. Any help would be greatly appreciated: Suppose X is a discrete random variable with P(X=0) = 2y/3 P(X=1) = y/3 P(X=2) = 2(1-y)/3 P(X=3) = (1-y)/3 Where 0<=y<=1. The following 10 independent observations were...

Standard ML help! datatype problem I have to create a function about peano numbers defined as the following datatype: datatype 'a peano = P of ('a -> 'a) * 'a -> 'a I have to create a function about peano numbers defined as the following datatype: datatype 'a peano = P of ('a -> 'a) *...

Homework Statement find <x>, <x^{2}> and \sigma of the probability distribution; \rho(x) = \sqrt{\frac{\lambda}{\pi}}e^{-\lambda(x-a)^{2}} Homework Equations As shown above The Attempt at a Solution I know that I can simply take the mean value (a) and the standard...

Given an imaginary, mechanical chimpanzee that never wears out nor sleeps nor relents. Who is compelled to type constantly through eternity into an endless text file using a US standard keyboard... as fast as he can. That this monkey knows simply that he must hit only character keys and only one...

Homework Statement write the standard form of the equation x^2-4x+8y+12=0 find the focus Homework Equations The Attempt at a Solution i have it down to (x-2)^2=-8(y-8) i'm not sure if you have to multiply the -8 on the right side of the equations by 4 since the focus is 1/4a

By definition standard deviation has divisor 'N' . But in Microsoft Excel the "STDEV" function gives 'N-1' as divisor. This may not be major issue to many of the people. But the command "STDEV" makes many users feel that this is standard deviation, i.e. it has divisor 'N'. Misleading...is...

A little background on my situation: I was a business major for 3 years before I switched to ME. As such, I've completed my school's core curriculum and have some spare time now that I'm in the ME program, being able to take only 8 - 12 hours per semester if I stay within the curriculum. So...

A block rides on a piston that is moving vertically with simple harmonic motion. (a) If the SHM has period 1.0 s, at what amplitude of motion will the block and piston separate? (b) If the piston has an amplitude of 5.0 cm, what is the maximum frequency for which the block and piston will be in...

The problem is to find a closed form for the expectation (mu) and standard deviation (sigma) of the probability density function underneath (Maple notation): f(t) = a*exp(a*t)*BesselK(0, 2*sqrt(exp(a*t)))/BesselK(1, 2) I was able to find an expression for mu:: mu =...

I am looking for a decent book (probably a textbook) that covers the standard model in its entirety (not necessarily in its vast detail, though). I am a physics undergrad in my 4th year, so I'm looking for something that gets into specific math and theory, but obviously not something that would...

Hi all, Does anyone know where I can find a tabulation of the standard Sloan/Johnson/etc astronomical filters? Any help would be greatly appreciated! :-) Natski

I calculated the standard enthalpy of a reaction using the constituent standard enthalpies of formations. My answer is in kcal / mol, how do I convert to J/g ? I know how to do the unit analysis BUT for the weight in grams... I imagine I use the weight in grams of the reaction - right? Would...

I've been reading most of the threads here in particle physics forum. Recently, I noted a couple of threads started by enotstrebor which were a bit impolitic. Nevertheless, they raised some issues which are similar to those I have myself with the Standard Model as well Quantum Mechanics in...

i would post this in the chem section but more people view this one.. im having a quiz on standard deviation in chemistry lab onf riday, and I am not sure AT ALL how to do this. i tried asking the teacher but he's not to good at explaining. and i tried lookinga t the difficult to understand...

Hello! Quick question: Is this valid: (\frac{standard \left \left deviation}{average} * 100)? The standard deviation is just a measure of the spread of the data from the average, so by doing the above, is it retaining its 'representation' as a measure of spread, just as a percentage of the...

Does anyone know how the standard equation is for a limit approaching a saturation limit x. I'm trying to model a concave down function where the dependent variable increases at a decreasing rate. see the graph below.

Quick question: why are the standard heats of formation 0 for pure elements?

I usually try to avoid asking how to do entire question sets, but I'm officially at loss at the moment. I need a point in the right direction. Homework Statement I have a ramjet that has a velocity of 2500 km/h, pressure is 40 kPa, and temperature is 240K Head addition is 1080 kJ/kG Velocity...

Homework Statement 4 C3H5N3O9 -> 12 CO2+10 H2O+6 N2 -- H rxn = -5678kJ Standard Heat of Formation of CO2=-394KJ Standard Heat of Formation of H2O=-242KJ Calculate the standard enthalpy of formation for nitroglycerin. Homework Equations Product minus reactant (I think) The...

Hey everyone, I was wondering if you could help me with something. Can someone give me the step to convert the two equations from general to standard form? If you could, it would be such a great help to me. Thanks y= x^2 - 2X + 5 and y= -3x^2 + 12x -4

I am stuck on a few cosmological points I could use some help on. The first being "redshift" as an indication of inflation. To me red shift just seems like it's a result of the degradation of light quanta over long distances. Since light slows down in environments close to absolute zero...

I need to calculate the average time of an event, and I'd like to calculate standard deviation as well. The problem is - there is no such thing as negative time - zero is a boundary - so how does it make sense if the average is 4000us (microseconds) and the stdev is 5000us? Is there a...

This is my first post. I am an aerospace engineer so these very technical computer questions still elude me. My question is mostly about RS422 standard. I have a piece of equipment (LIDAR) that is able to transmit data via a 9 pin serial port. If you put a jumper across two of the pins it...

Hi I have a question. Let X1 & X2 be stochastic variables and X1<=X2, then can we say E[X1]<=E[X2] or SD[X1]<=SD[X2]? why or why not? Looking forward to some reply Thanks!

Hi guys, here i have two question, but i don't understand the answer at all. For the standard enthalphy change question 5) b) i) shouldn't it be standard enthalphy change = Product - Reactant? But from the answer it was given as reactant - product. For question number 8, i don't understand...

Hi guys, I've got this question where i am abit confused by which value should be used. Predict if a spontaneous reaction takes place between a) H2O2 and Cl2 b) H2O2 and I2 c) H2O2 and KI 1/2 Cl2 + e- \rightarrow Cl- (E = +1.36) --- 1 1/2 I2 + e- \rightarrow I- (E =+0.54) --- 2...

i have a vent that is too fast and too loud, and it runs off of US standard ac. i was wondering if there is a (good brand name) device that could limit the rms voltage. i don't want a pair of resistors, that would heat up real fast. i need the voltage cut in half, approximately. an analog...

Have loop quantum theorists looked forward to how one might fit the standard model into loop quantum gravity? Thank you for any help.

Homework Statement http://img338.imageshack.us/img338/5064/picture1nk.png 2. The attempt at a solution I know the area for -1.5 is .0668. I also know that the area of the positive half of the curve is .5000. I don't know how to figure out what the other blue piece is or how much the white...

Homework Statement I am a GCSE Physics student, and my teacher recently set us a homework sheet in which he said contained questions 'exceeding A-Level standard'. He told us to get as far as we could. So, I have completed 12 of 18 questions, but I am very confused about the last 6: 1) A...

Hi, How do you calculate the Mean and standard error of a data set without having to crunch all the numbers? I have a set of data with 45 entries and numbers in the tens of thousands and was wondering if there was a way to calculate these without have to punch hundreds of number into a...

In the article "The Lattice Theory of Quark Confinement", by Claudio Rebbi (Scientific American) there is a graphic representing the chromoelectric field. The caption reads: "Chromoelectric field is a gauge field similar in principle to the electromagnetic field but more complicated...

Hi, I have a regular OLS regression that includes a variable both by itself and squared (i.e. y=b0+b1*x+b2*x^2). I am interested in the marginal effect of the variable at the mean. I know how to get the point estimate, but does anyone know how to get standard errors for the marginal effect...

Hi, can someone just confirm that to get the GSD of a distribution, I simply take the natural log (or log 10?) of all the numbers then find the arithmetic standard deviation of that? Thanks :)