A study of iron deficiency among infants compared blood hemoglobin levels of a random sample of one-year-old infants who had been breast-fed to a random sample of one-year old infants who had been fed with standard infant formula.

Here are the results.

n x s

Breast-fed infants 31 15.3 1.6

Formula-fed infants 35 13.4 1.9

We wish to test the hypothesis 0 : 0 H B F = against : 0 HaB F , where B and F are the population mean blood hemoglobin levels for breast-fed and formula-fed infants, respectively.

(a) What additional information would you need to confirm that the conditions for this test have been met?

(b) Assuming the conditions have been met, calculate the test statistic and P-value for this test.

(c) Interpret the P-value in the context of this study, and draw the appropriate conclusion at the = 0.05 level.