.
. centre de ressources dilemmes et doutes le visage humain de mathématiques Qui sommes-nous Problème de mois activités de promotion babillard
Centrale des maths - centraledesmaths.uregina.ca
Dilemmes & doutes
« D & D »
. .
topic card  

Sujet:

interval

liste de
sujets
. .
nouvelle recherche

17 articles trouvés pour ce sujet.
 
Page
1/1
La somme de deux fonctions 2007-11-19
maud pose la question :
Consigne : Ecrire la fonction f comme somme de deux fonctions u et v définies sur I. Donner le sens de variation de u et de v sur I. En déduire le sens de variation de la fonction f sur l'intervalle I indiqué. f(x)=-2x+(1sur x) I=]0;+infini[

Correction : Sens de variation de f sur I=]0;+infini[ On a f(x)=u(x) + v(x), avec {u(x) = -2x et v(x) = 1sur x La fonction u est strictement décroissante sur R, donc sur I ( droite avec coefficient directeur -2 négatif). La fonction v qui est la fonction inverse est stricyement décroissante sur [0;+infini[. Donc, la fonction f = u+v est strictement décroissante sur [0;+infini[.

Ma question : Pourquoi la fonction v et la fonction f ne sont pas définies sur le même intervalle que la fonction u c'est-à-dire sur l'intervalle I indiqué ?

Claude Tardif lui répond.
Positive and negative values of a function 2018-01-30
Grayson pose la question :
f(x)=x^6-x^4
Interval: ( negative infinity, negative one )
Test Value: negative two
Function Value f(x): positive forty eight
Interval: ( negative one, zero )
Test Value: negative one
Function Value f(x): zero
Interval: ( zero, positive one )
Test Value: positive one
Function Value f(x): zero
Interval: ( positive one, positive infinity )
Test Value: positive two
Function Value f(x): positive forty eight

What is the sign of f(x) for each Interval?

Penny Nom lui répond.
Continuity on a closed interval 2014-09-21
Pragya pose la question :
The trouble I'm having is as follows :
a continuous function is most of the times defined on a closed interval, but how is it possible to define it on a closed interval ,because to be continuous at endpoints of the interval the function's limit must exist at that endpoint,for which it has to be defined in its neighborhood,but we don't know anything about whether the function is always defined in the neighborhood.
Please help...

Penny Nom lui répond.
Differentiable on an interval 2010-08-12
Dave pose la question :
Hi I was wondering if a function can be differentiable at its endpoint. For example if I have Y = X^2 and it is bounded on closed interval [1,4], then is the derivative of the function differentiable on the closed interval [1,4] or open interval (1,4). They always say in many theorems that function is continuous on closed interval [a,b] and differentiable on open interval (a,b) and an example of this is Rolle's theorem. Thank you for your help.
Robert Dawson lui répond.
Sample size 2010-03-29
Rae pose la question :
What sample size was needed to obtain an error range of 2% if the following statement was made? "75% of the workers support the proposed benefit package. These results are considered accurate to within + or - 2%, 18 out of 20 times. This seems like a straight forward question but I'm getting it wrong. Could you please help me out even just the set up would be appreciated so I can see if that's where I'm going wrong. Thanks
Harley Weston lui répond.
The intervals where the function is positive and negative 2010-01-10
Ron pose la question :
Hello

I'm trying to find out the intervals where the function is positive and negative. It's for a polynomial function y= -(x+2)^2 (x-2) and y= (x+1)(x+4)(x-3)

I have tried the right and left side of each x-intercepts, but I still don't understand the results

thank you for your help

Penny Nom lui répond.
Percent change between two value ranges 2007-11-28
Joe pose la question :
How do you calculate a percent change between tow value ranges - for instance if I project a range for 2007 to be between 100 and 120 and a range for 2008 to be between 120 and 140, how do I calculate the estimated increase between the range? Is it 0% to 40% (taking the two inside values rto calculate the minimum and the two outside values rto calculate the maximum?)
Harley Weston lui répond.
Find the sample size needed 2007-05-13
Mini pose la question :
Find the sample size needed to be 98% confident thata marketing survey on the proportion of shoppers who use the internet for holiday shopping is accurate within a margin of error of 0.02. Assume that the conditions for a binomial distribution are met, and that a current estimate for a sample proportion does not exist.
Penny Nom lui répond.
Interval of the domain 2007-05-13
Gale pose la question :
What does the term interval of the domain mean?
Penny Nom and Stephen La Rocque lui répond.
Write the interval in absolute value notation 2007-03-20
Timothy pose la question :
1. Write interval in absolute value notation
i) xE[0,9]
ii) xE[-2,20]

Penny Nom lui répond.
A confidence interval 2006-01-21
Jonathan pose la question :

I am attempting to calculate how my confidence interval will widen at the 95% confidence level if my response universe increases from 100 to 150 or to 200.

There is a universe of 54,000. I take a 5% sample for a test universe of 2,700

If my "yes" universe is 100, at the 95% confidence level, what is my +/- range? (i.e +/- 3? +/-5?)

Historically, 6.6% of the 2,700 you say "yes". I am trying to determine how the confidence interval would change if the number of "yes" responders increased to 150 or to 200.


Penny Nom lui répond.
Computing confidence intervals 2004-11-26
Christie pose la question :
I was given a question with N=100, sample proportion is 0.1- compute the 95% confidence interval for P? I have tried this several ways but do not know how to do without means, standard deviations, standard error of the mean? I asked my teacher and she said I have all the info I need. Can you help????
Penny Nom lui répond.
Sampling distributions 2002-02-18
A student pose la question :
  1. given: n = 40, standard deviation is not known, population of individual observations not normal. does the central limit theorem apply in this case? why or why not?

  2. for an estimation problem, list two ways of reducing the magnitude of sampling error?

  3. What will happen to the magnitude of sampling error if the confidence level is raised all other things remaining the same? justify your answer?

Harley Weston lui répond.
A sample size problem 2001-10-28
Charles pose la question :
The U.S Transportation Dept. will randomly sample traffic reports to estimate the proportion of accidents involving people over the age of 70. The Dept. has no advance estimate of this proportion. how many reports should the dept select to be atleast 97% confident that the estimate is within .01 of the true proportion?
Harley Weston lui répond.
A confidence interval 2001-06-28
Murray pose la question :
An investigator wants to find out of there are any difference in "skills" between full and part time students. Records show the following:
Student            Mean Score         Std Dev        Number
----------      -----------------     ----------     -----------
Full time              83                   12          45
Part time               70                   15          55
Compute a 95% confidence interval for the difference in mean scores.

Andrei Volodin lui répond.
A confidence interval 2001-04-26
Kim pose la question :
A poll asked 1528 adults if they were in favor of the death penalty, 1238 said yes, find 99% confidence level for percent of all adult who are in favor of the death penalty.
Andrei Volodin lui répond.
Estimating the population mean 1999-11-13
John Barekman pose la question :
Statitistics: Estimating the population mean when the standard deviation is known:

I am not sure which n to use in the formula for the confidence interval equation:

x +/- z*(standard deviation/sqrt(n))

If we have data of ten people, and if we have the data of ten sets of ten people each, what is the difference in the n that we use? What is the difference between the standard deviation and the standard error? Are we using the number of sampling means or just the number of samples?
Harley Weston lui répond.

 
Page
1/1

 

 


Centrale des maths reçoit une aide financière de l’Université de Regina et de The Pacific Institute for the Mathematical Sciences.

CMS
.

 

accueil centre de ressources accueil Société mathématique du Canada l'Université de Regina PIMS