2. A study of iron deficiency among infants compared samples of infants following different feeding regimens. One group contained breast-fed infants, while the infants in another group were fed a standard baby formula without any iron supplements. Here are summary results on blood haemoglobin levels (grams per deciliter (g/dl)) at 12 months of age: (a) (b) Group Sample size Sample mean (g/dl) sample standard deviation (g/dl) Breast-fed 36 17.3 2 Formula 49 16.4 3 Test if the mean hemoglobin level is higher among breast-fed babies. Use the 1% significance level. (8 marks) Obtain a two-sided 99% confidence interval for the mean difference between the two populations of infants. (4 marks)