intervals

  1. H

    Intervals

    Hello, i am having trouble with a problem Here is my work, (1/x-2) >= (3/x+1) i first multiply both sides my x + 1 and get, (x+1/x-2) >= 3 then i subtract 3, (x+1/x-2) - 3 >= 0 then i mult to get a common denominator, (x+1/x-2) - (3x - 6/x-2) >= 0 combine like terms, -2x+7/x-2 >= 0 so...
  2. K

    increasing/decreasing intervals of a polynomial

    Came across this question in a few tests from sosmath.com: On what interval(s) is the function f(x) = x^3 - 3x decreasing? The zeros are +/- sqrt(3) and 0. Given the end behavior of a third degree polynomial with positive leading coefficient, I assume that it crosses x-axis at...
  3. K

    Confidence intervals and hypotheses

    Hey guys I had a quick question I came across while studying that I don't know how to do. Any help at all is greatly appreciated I have a "coefficient molecule ratio" that measure the effect of the faces of golf clubs. I have 15 golf clubs produced from the same maker that were randomly...
  4. A

    Prediction Intervals

    I'm doing the part where it says, "Assuming a normal distribution of tonsil strengths, give a lower 95% prediction limit on a single observed tensile strength value". For this we use a t-distribution table. The sample size is n = 50, so v = 49. If you look at the table it only has 40 and then it...
  5. P

    Confidence Intervals Question Checking work

    Hello! I'm looking for any kind of advice to start this problem. Please don't just give me the answer. Explain how to do the problem! Thanks! Suppose we are interested in modeling the distribution of tread life for a premium brandof radial tire. Assuming that the life of the tires are normaly...
  6. G

    Confidence Intervals for not integers numbers ratio

    Hi, I’m having a problem with a particular case of binomial proportion. I want calculate a confidence Intervals for a binomial proportion for an efficiency. This kind of intervals are usually defined for ratios between integers numbers but in my case I had to subtract from both numerators...
  7. G

    Confidence Intervals for not integers numbers ratio

    Hi, I’m having a problem with a particular case of binomial proportion. I want calculate a confidence Intervals for a binomial proportion for an efficiency. This kind of intervals are usually defined for ratios between integers numbers but in my case I had to subtract from both numerators and...
  8. A

    Question concerning covering the rationals with open intervals (paradox?)

    The following seems paradoxical. Consider the following countable collection of open intervals: I1 is ( 0, 1/2 ), I2 is ( 1/2, 3/4 ), I3 is ( 3/4, 7/8 ), etc. The sum of the lengths of the intervals is 1. Now cover each rational number with one of the intervals. Either 1) two successive...
  9. M

    prove that the set of all intervals with rational end points is countable

    can anyone help with this question. this si my work. i know it is incomplete clearly, rationals are coutable let S be the set of all the intervals with rational end points. then S is subset of QxQ let h be a mapping such that h:NxN->S. here S is coutable since h is bijective. where do i...
  10. B

    Possible to combine Confidence Intervals, same popluation?

    Hello! Complete novice here (allied health student): Is there a simple way for me to extract a single Mean/CI from two given for separate, consecutive time periods? - Same subjects; same intervention/control. - For a basic analysis- one paper of many so minimal detail is required. I don't have...
  11. C

    Decreasing intervals

    f(x) = x^4 - x^2 -4 f'(x) = 4x^3 - 2x c = 0, 1/sqrt(2) drew number line and picked arbitrary point between intervals. f'(-1)= negative f'(1/4)= negative f'(2)= postive so its suppose to be (-infin, 0) U (0, 1/sqrt(2)) my answer is not matching up, help :(
  12. C

    increasing intervals

    Find the intervals on which f(x)= 3 + 4x - 2x^2 - x^3 is increasing.. my work... f'(x) = 4-4x-3x^2 = 0 c= 2/3, -2 drew out my number line and chose a arbitrary value between the intervals f'(-3) = positive f'(-1) = negative f'(1) =positive therefore.. my interval is increasing at...
  13. C

    Confidence Intervals

    Can someone please help with this problem. I keep getting Error: Domain when I put it in the TI83 calculator. A grocery store keeps records of the wait times for its checkout lines and finds that when 201 experiences were recorded the mean wait time is 5.2 minutes with a standard deviation of...
  14. K

    sign table method for positive and negative intervals of a graph

    To use the sign table method to find where a graph is increasing or decreasing , when the intervals are chosen how are signs determined for each interval?, is a number outside or inside each interval chosen and put into the function, the function is worked out and the sign is chosen depending on...
  15. A

    intervals of decrease and increase help

    I have a question that gives the function as f(x)=x3-x2+4x-3 and the following questions, a) find the intervals of increase and decrease. b) the location of any maximum or minimum points. c) the intervals of concavity up or down. d) the location of any points of inflection. I'm stuck on...
  16. C

    absolute equation w/ piece wise intervals

    I don't really know what im doing.
  17. K

    Intervals of increase/decrease with an asymptote

    I found the derivative of the original function and set it equal to zero to give me my critical pts. I then tested each interval and found whether the slope was pos. or neg. in each interval(pos -2 neg 2 pos). However when I graph the original f(x) there is a vert. asymptote at x=0. Is...
  18. S

    Relationship between confidence intervals and hupothesis testing

    For the avoidance of ambiguity, the definition of confidence interval i am using is : "If independent samples are taken repeatedly from the same population, and a confidence interval calculated for each sample, then a certain percentage (confidence level) of the intervals will include the...
  19. A

    Wald and likelihood ratio based confidence intervals

    Hi all I have a problem with the two types of C.I. that I produced for my MLE. The two confident intervals are very different, that LR C.I. are (2.7 and 3.15) and Wald C.I. are (2.3, 3.5). LR CI is much smaller than Wald CI. For Wald, I calculated the standard error using Hessian matrix from...
  20. A

    95% confidence intervals

    I have data that is very right skew where I know the sample mean, the sample standard deviation and the sample size. I have calculated a 95% confidence interval for the mean using the following method: (mean-1.96xESE, mean+1.96xESE) where ESE is estimated standard error. The question then asks...