The mean potassium content of a popular sports drink is listed as 140 mg in a 32-oz bottle. Analysis of 20 bottles indicates a sample mean of 139.4 mg.
(a) Write the hypotheses for a two-tailed test of the claimed potassium content.
(b) Assuming a known standard deviation of 2.00 mg, calculate the z test statistic to test the manufacturer's claim.
(c) At the 10 percent level of significance (α = .10), does the sample contradict the manufacturer's claim?
(d) Find the p-value.