xbar

  1. P

    Hypothesis test (xbar as estimator of mu)

    Hi all, could you help me solve the following problem ? A new fuel is tested for cars in order to increase the number of km. A test take place in 16cars and shows that x_bar = 17.5km/lt and standard deviation s=2km/lt. We know that mu=17 and sigma=1.8km/lt. A)What is the probability of xbar...
  2. X

    Getting a new distribution for X(bar)

    Let X(bar) be the mean of a random sample of size 12 from the uniform distribution on the interval (0,1). Approximate P(1/2 < X(bar) < 2/3). No idea how to do this whatsoever. I know you can use the moment generating function but I can't simplify it to make it work. And sorry I can't...
  3. H

    X-bar charts -- Upper/lower control limits

    When calculating the Upper Control Limit for X-Bar Charts, how do you know which "A2" figure from the control chart to use in the calcuation. The formula is : x-double bar - A2 x RBar Yes, I've looked in my class notes but they seem to use a different A2 figure for every example. How do I know...
  4. A

    Finding xbar and standard d...

    population of 18000. 10% are assigned letter grade of A (given only to those 475+) 80% are letter grade of B (ranges from 25-475) 10% are letter grade of C (25 or less) Assume normal distribution... So, I have taken 475-25, div by 2 to get the midpoint of the distribution, which is 225...
  5. M

    hypothesis testing/Critical Region, must i find μ or XBar?

    ok guys, im not askng you to do my homework, but i could use a point in the right direction.. ive got one of those fun filled packets where each question depends on the previous answer, so if i start it right i should be ok.. Background - many studies over the years have established...
  6. C

    Is this right? Finding x-bar

    I don't have an answer to check against but could someone let me know if I did this right? Formula for xbar: x bar = \frac{My}{m} Finding m: m = p \int_{\sqrt{3}}^{0} \frac{1}{x^2+1} m = p ( arctan(\sqrt{3})) Finding My: My = p \int_{0}^{\sqrt{3}} x * \frac{1}{x^2+1} My = p...