There is convincing evidence that breastmilk containing antioxidants is important in the prevention of diseases in infants. Researchers A. Xavier et al. studied the effects of storing breastmilk on antioxidant levels in the article “Total Antioxidant Concentrations of Breastmilk—An Eye-Opener to the Negligent”. Samples of breastmilk were taken from women and divided into fresh samples that were immediately tested and the remaining samples that were stored in the refrigerator and tested after 48 hours. A hypothesis test is to be performed to decide whether, on average, stored breastmilk has a lower total antioxidant capacity.

Hypothesis tests are proposed. For each hypothesis test,

a. Identify the variable.

b. Identify the two populations.

c. Identify the pairs.

d. Identify the paired-difference variable.

e. Determine the null and alternative hypotheses.

f. Classify the hypothesis test as two tailed, left tailed, or right tailed.