the UB to LB distance is equal to +/- Z (stdev/sqrt(n)). So UB - LB = 2*Z*stdev/sqrt(n) solving for sqrt(n), I have
sqrt(n) = 2*Z*stdev/(UB-LB) and n = (2*Z*stdev/(UB-LB))^2 If an example is not in your book, this or something like it should be. That's how we estimate required n, given a desired UB-LB. Jay Paul H wrote: > > The following is the upper and lower bounds of a measurement of size from a > sample from a production process. > > LB = 28.75 > UB = 81.25 > > Sample Mean is 65, Variance is 225. Distribution is normal. > Please excuse the cross post.. > > I need to determine the level of confidence associated with those intervals? > I know I need to use the following formula. > > Sample Mean +- Z (SD/SQRT(N)) > > I know the mean and SD. Problem is I don't know the sample size n. How do I > get it? Any help greatly appreciated... > > . > . > ================================================================= > Instructions for joining and leaving this list, remarks about the > problem of INAPPROPRIATE MESSAGES, and archives are available at: > . http://jse.stat.ncsu.edu/ . > ================================================================= -- Jay Warner Principal Scientist Warner Consulting, Inc. 4444 North Green Bay Road Racine, WI 53404-1216 USA Ph: (262) 634-9100 FAX: (262) 681-1133 email: [EMAIL PROTECTED] web: http://www.a2q.com The A2Q Method (tm) -- What do you want to improve today? . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
