1. The problem statement, all variables and given/known data A machine produces metal pieces that are cylindrical in shape. A sample of pieces is taken and the diameters are found to be 1.01, 0.97, 1.03, 1.04, 0.99, 0.98, 0.99, 1.01, 1.03 centimeters. Find a 99% confidence interval for the mean diameter of pieces from this machine, assuming an approximately normal distribution. 2. Relevant equations 3. The attempt at a solution From our data, we know N = 9. We find the sample mean X(bar) = 1.0056 and standard deviation s = ? (how exactly do we find this? Do we use the equation (1/n-1) * Ʃ (Xi - X(bar))2?. Moving on.. Since we have a normal population but UNKNOWN population variance, we muse use the t statistic: α = 0.01 and tα/2 = 3.355 from the t-distribution table. 1.0056 ± (3.355) * s / √9 and then compute. Is this the way? Also, like I asked before, how do we find s exactly from our data?