Results 1 to 2 of 2

Math Help - Quality Control Problem

  1. #1
    Junior Member
    Joined
    Dec 2008
    Posts
    33

    Quality Control Problem

    Hi ,

    Any help at all will be appreciated with the following question.

    Q.) 1. Samples of n = 4 items each are taken from a manufacturing process at regular intervals.

    Suppose the process mean u = 200 and the standard deviation o = 10.

    a. Find both the 3 sigma control limits and the probability limits (a = 0.002) to control the process mean.

    b. Find the average run length and the standard deviation of the run length for both charts (in a.), in the following cases: i) process is in control, ii) process mean shifts to u1 = 209.

    c. For both charts in a., what is the required sample size to detect this shift in the process mean on the first or second sample following the shift with the probability >= 0.9? For which of the two charts is the required sample size bigger and why?

    d. Assume that the following rule is applied to the control chart with 3 sigma limits constructed in a. The process is declared out of control when either a point plots outside the 3 sigma limits or two consecutive points plot between the two and three sigma control limits on the same side of
    the control chart. If the process mean shifts to u1 = 209, what is the probability that the shift will be detected on the first sample following the shift?

    I attempted it and here are the answers I got:


    a.) 3 sigma: UCL: 215 LCL: 185
    Probability limits: 215.45 and 184.55

    b.) 1 and 8.69

    c.) n> 0.03 !

    d.) not sure.

    Please correct me where I'm wrong and guide me through this question. If some one can give me the correct answers, I'll get the right solution eventually hopefully.

    ...
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member
    Joined
    Dec 2008
    Posts
    33

    Illegal bump

    A little help please.

    Thank you.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Quality Control?
    Posted in the Advanced Statistics Forum
    Replies: 8
    Last Post: May 4th 2011, 01:31 PM
  2. Optimal control problem
    Posted in the Calculus Forum
    Replies: 1
    Last Post: September 29th 2010, 04:20 PM
  3. Statistics and Risk Analysis in Quality Control
    Posted in the Advanced Applied Math Forum
    Replies: 0
    Last Post: August 23rd 2009, 09:41 AM
  4. Quality control of electric bulbs
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: November 2nd 2008, 07:57 PM

Search Tags


/mathhelpforum @mathhelpforum