Free response question

A study of iron deficiency among infants compared samples of infants following different feeding regimens. One group contained breast-fed infants, while the children in another group were fed a standard baby formula without any iron supplements. Here are the results on blood hemoglobin levels at 12 months of age.

Groupn​​ s 

  ​______________________________________________

​Breast-fed​23​13.3​1.7

​Formula​19​12.4​1.8

a).​Is there significant evidence that the mean hemoglobin level is higher among breast-fed babies? Give appropriate statistical evidence to support your conclusion.

b) .​Construct a 95% confidence interval for the mean difference in hemoglobin level between the two populations of infants. Interpret your interval in the context of this problem.