Farnum (1994) discusses a chrome plating process. Small electric currents are run through a chemical plate that contains nickel, resulting in a thin plating of the metal on the part. Since the bath loses nickel as the plating proceeds, the operators periodically add more nickel to the bath. Operating standards call for a nickel concentration of 4.5 oz/gal. The process runs three shifts per day. The following are the bath concentrations at the beginning of the day for five days. Assume that these concentrations form a random sample: 4.8, 4.5, 4.4, 4.2, and 4.4.
a. Conduct the most appropriate hypothesis test using a 0.05 significance level. Discuss your conclusions about the chrome plating process based in this analysis
b. Construct a 95% confidence interval for the true mean concentration.
c. Construct a 95% prediction interval for the concentrations