A cohort study in Johannesburg assessed infant feeding practices and the risk of infant HIV infection at 3 months of age. A total of 941 HIV infected mothers and their infants (HIV negative) were enrolled. These mother-infant pairs were divided into exposure groups with respect to feeding practices, including exclusive breastfeeding (n=91) and mixed feeding (n=355). By three months of age, eleven (11) of the exclusively breastfed babies and seventyseven (77) of the mixed feeding babies had developed HIV infection. 1.1 Construct a two-dimensional contingency table (2x2) of the above data? (5) 1.2 Calculate and compare the incidence of outcome (HIV status) in the two groups. Please offer an explanation or interpretation of your result.