Statistics Definition and 998 Threads

Homework Statement I am given the lens maker's equation: 1/u + 1/v = 1/f Then told that U and V are random variables based on this equation. U is uniformly distributed between 2f and 3f. The question is to prove the pdf of V is f/(v-f)^2 and find the cdf for V. Also - find the...

Well the questions and solutions are in one for some and I will type out the rest. Q6 http://img249.imageshack.us/img249/2757/47026197.jpg Q4 http://img237.imageshack.us/img237/1802/93774799.jpg Q3 http://img3.imageshack.us/img3/5919/34981698.jpg Q1...

Homework Statement The electricity usage (KWh) in homes was studied over a period of time. For Year 1: Mean = 1130 Std dev. = 196 n = 16 For Year 2: Mean = 1350 Std dev. = 302 n = 21 a) Test the hypothesis that the std dev. in year 2 has increased compared to year 1...

Hi there, I have a question regarding infinity and statistics. (I hope there aren't too many questions with infinity on these forums) I was wondering if you had some simple procedure, like say rolling a six sided die, and said you did this an infinite amount of times, would it be valid to...

Homework Statement given distribution function F(t)=1-(1+t)^-c, 0<_t<_infinity, c>0. And that a company claim the median lifetime of a component is at least 7 years and that a component fails after 2.22. Using only this information test the claim that the median lifetime is in fact shorter...

Homework Statement In the Drude model the probability of an electron having a collision in an infinitesimal time interval dt is given by dt/\tau. (a) Show that an electron picked at random at a given moment will have no collisions during the next t seconds with probability e-t/\tau. (b) Show...

Hey everyone! Spring semester recently started for me and I am really getting stressed out as I am trying to lay a solid plan for my future. First, a bit of information about myself: Sophomore honors student at a pretty decent state school. B.S. in Mathematics and Economics (4.0 GPA in...

***SOLVED*** Homework Statement A system of particles is at equilibrium. What is the proportion of particles in the ground state? The Attempt at a Solution P(\epsilon_{s})=\frac{exp(-0/\tau)}{1+exp(\frac{-\epsilon_{s}}{\tau})+exp(\frac{-2\epsilon_{s}}{\tau})} Is that right? This is a...

Greetings I became interested in technical sciences only last year (I'm a historian) and started studying on my own. Just finished Multivariable Calculus and Linear algebra with Paul's online math notes. (for those who may know about this page yet: http://tutorial.math.lamar.edu/) Now I'm...

Homework Statement It's problem 1. (b) in the attachment. I need help finding the average number of records. Note: Obviously, I'm not actually in the class. I just got bored and started going through the course assignments Homework Equations From the first part of the question, I...

Hey all, I will soon be graduating with a MSc in Transportation Engineering. I'm currently writing my thesis, and probably by May 2010 will be done. However, I am unsure I am willing to go for a PhD, at least not in this field. During my time in my Master, I found out I can only do...

This should be a very easy problem, i just can't seem to find what makes the center, shape and spread. The distribution of actual weights of 8-ounce chocolate bars produced by a certain machine is normal with mean 8.1 ounces and standard deviation 0.1 ounces. Company managers do not want the...

Not sure if this is much of guidance, but seemed to be the best category? Is there a place where I can check nationwide statistics for Undergraduate Physics enrollment? I know that Physics I and II always have a good enrollment of 15-25 students, but as soon as it crosses that upper level...

Can a photon gas undergo a Bose Einstein condensation ?

I want to study it myself recently ~but I don't know where to start ? Can anyone help me ? XD

"the probability to buy a suite is 0.22 the probability to buy a shirt is 0.3 the probability to buy a tie is 0.28 the probability to buy a suite and shirt is 0.11 the probability to buy a suite and tie is 0.14 the probability to buy a tie and shirt is 0.28 what is the probability that...

Homework Statement Consider an atom with a magnetic moment \mu and a total spin of ½. The atom is placed in a uniform magnetic field B at temperature T. (a) Assuming Maxwell-Boltzmann statistics are valid at this temperature, find the ratio of atoms with spins aligned with the field to those...

Homework Statement Let Y1<Y2<...<Yn be the order statistics of a random sample of size n from the pdf f(x) = e^{-x} x ranging from 0 to infinity. a) Show that Z1=nY1, Z2 = (n-1)(Y2 - y1) Z3= (n-2)(Y3-Y2)... Zn = Yn - Y_(n-1) are independent and that each Z has the exp distribution...

For the following tests of significance 1 tests of mean difference for paired data - differences a calulated - forms a new random variable test its mean 2 two sample normal tests - looks at the differences in averages i have trouble picking which one to use for problems, i mean...

Im currently doing an introductory stats course and have learnt: - poisson distribution - binomial distribution - normal distribution - t-student - and chi-square I think I know what most of them look like but am having a bit of a hard time distinguishing what distribution to use when...

Homework Statement Let X1,X2,X3,Y1,Y2,Y3 be random variables. If X1 and Y1 have the same distribution, X2 and Y2 have the same distribution, X3 and Y3 have the same distribution, then is it true that X1+X2+X3 and Y1+Y2+Y3 will have the same distribution? Why or why not? 2. Homework...

Theorem: Let {N(t): t≥0} be a Poisson process of rate λ. Suppose we are given that for a fixed t, N(t)=n. Let Ti be the time of the ith event, i=1,2,...n. Then the (conditional) density function of Tn given that N(t)=n is the exactly the same as the density function of X(1)=min{X1,X2,...,Xn}...

The question reads exactly as follows, Find the appropriate values for #'s. a) P(Z<#)=.9 b) P(|Z|<#)=.9 We are currently going over distributions, poissons, density functions and binomial stuff, someone referenced to Z-values from a ztable but i don't know if this is what the topic...

Hello, Suppose that we have the following set of independent and identically distributed RVs: \gamma_1,\,\gamma_2,\,\ldots,\,\gamma_M. Arranging them in descending order as: \gamma_{1:M}\ge\gamma_{2:M}\ge\cdots\ge\gamma_{M:M}. Now suppose we select the largest m\leq M order statistics. What...

1) My wife and I are very athletic. Between us, we jog an average of 5 miles a day. My wife jogs 10. 2) In freeway driving, my car averages 32 miles per gallon. 3) Last year my car repairs averages $48 per month. 4) The average statistician has 3.46 children. 5) The average fuse time...

I am having trouble with what seems to be a simple combinations or permutations problem as follows: Melodies for more than 14,000 songs are listed according to the following scheme" The first note of every song is represented by anasterisk * and successive notes are represented by R (for repeat...

Biting an unpopped kernel of popcorn hurts! As an experiment, a self-confessed connoisseur of cheap popcorn carefully counted 773 kernels and put them in a popper. After popping, the unpopped kernels were counted. There were 86. How do I do this? (a) Construct a 90 percent confidence...

Would you agree that statistics can be mathematically misrepresented to prove most related arguments both true and false?

Really stuck on this question. Stock A has an expected return mean of 0.03 and standard deviation of 0.02 Stock B has an expected return mean of 0.02 and standard deviation of 0.01 Investor invests in 20 lots of stock A and 15 lots of Stock B (as in 4/7 in A and 3/7 in B) What is the...

Homework Statement let f(x) be a density on R+ (so f(x) < 0 if x < 0). Let g(x,y) = f(x+y)/(x+y), x > 0, y> 0 a) show g is a density on R^2 b) assume that the expectation u and variance sigma^2 associated univariate density f exist and that mu^2 does not equal 2sigma^2. Show that X and Y...

Hello all, we have the B-E function <n>=1/(exp(x)-1), where x is hv/kT. What is <n> actually? because i ready everywhere that it is average no. of phonons! but it also probability..? Please explain clearly all terms involved in the above relation.. thanks

Homework Statement not exactly sure were this goes ok there was a question that my teacher told me i got wrong the question asked me to compute the mean which I did... then the question went on to tell me compute the mean with another observation equal to zero then the part that...

Hello. Does anyone here have some resources about "probability and statistics for biomedical engineers" or "probability theory","random processes" ? I do need it. Thanks in advance!

Any thoughts on "Introduction to Mathematical Statistics" by Hogg, Craig, and McKean? Dear PF members, I was looking for a textbook for my mathematical statistics course, and it turns out that Introduction to Mathematical Statics by Hogg, Craig, and McKean will be the book for the course...

I am curious about what insight people might have as to the statistics of Navier Stokes equation. I thought of the following way someone might try to calculate these. 1) Choose a bais (Basis A) 2) Pick a discrete number of points to constrain the solution of stokes equation. 3) Find the...

To those familiar with university structure, mine offers two different statistics courses (besides those that are offered to fields like soc. or bio. which are not open to non majors). One is offered by the statistics department, one by the math department. Is there a generalized difference...

Hello Forum, I am not clear on what higher order statistics actually mean. I know that if a process is Gaussian, it is fully described by its mean and variance. The higher order statistics are zero or redundant...IF the process is not Gaussian, then the HOS are useful... 1) How do we...

10. The birth weights (in kilograms) are recorded for a sample of male babies born to mothers taking a special vitamin supplement (based on data from the New York Department of Health). When testing the claim that the mean birth weight for all male babies of mothers given vitamins is equal to...

Homework Statement Let Y1, Y2, ..., Yn denote a random sample from the uniform distribution on the interval (\theta, \theta + 1). Let \hat{\theta} = Y_{(n)} - \frac{n}{n+1} Show that \hat{\theta} is an unbiased estimator for \thetaHomework Equations Well, to check for unbiasedness...

Hi People. I was looking at the derivation(s) of Fermi-Dirac Statistics by means of the "most probable distribution" (I know the correct way is to use ensembles, but my point is related to this derivation) and it usually employs Lagrange multipliers and Stirling's approximation on the...

question chapter 4 case 6 - from book "complete business statistics 6th edition-aczel and amir" A company sells machines to four customers in four different countries. It has to be sell two months from now. The following is a table of information of selling price, exchange rate. The selling...

Homework Statement f(x;theta)=Exp(-x+theta) Find parameter estimates for variable 'theta' using maximum likelihood Estimator and Method of Moments. Homework Equations Log(x; theta) = Log(Exp(-x + theta)) -- For MLE Integral from theta to infinity of (x*Exp(-x + theta)) = xbar -- For Method of...

HI I'm not to sure where to place this post. I'm looking for a computer application where I could plug values into get charts , bar graphs pie charts etc. I do not have very much experience in this field , but I want to play around. If you guys know of any great programs that can produce...

Once you become a physicist how hard is it to get a job in the field (any field)? Is it bleak and nearly hopeless or is it easier than I think it is. I don't really want a job at a university so are the many opportunities at other places for research? Does anyone know where I could find any...

Homework Statement Hi, the problem that I am struggling with is getting an appropriate method to produce non - linear line of regression when the data follows non - linear pattern.Homework Equations Would it be appropriate to use Newton's interpolating polynomial or Lagrange's polynomial at...

any ideas on an introductory statistics book with a good deal of rigor? thanks.

Homework Statement Two cards are dealt from a deck of 52 cards. Find the probability that at least one of them is an ace. The Attempt at a Solution This is for an intro. stat class and the material is very simple but for some reason I cannot find this answer. The only attempt that...

which one is more marketable/versatile? can you get a job from just getting a bachelor's in either one of them? gracias

The exercisie is in the attachment. I am trying to solve it using a Binomial distribution, using n = 64, and p = 0.2. P(X=1) = (64) (0.2)^1 (0.8)^63 ( 1) and, I get that P(X=1) = 1.00434 * 10^-5 However, this does not seems correct, can anyone help me here?? I need to submit...

Homework Statement In considering the safety of building, the total force acting on the columns of the building must be examined. This would include the effects of the dead load, D, due to weight of the structure, the live load, L, due to human occupancy, movable furniture and the like, and...