Hybrid offspring of parents of different species are often sterile. How different must the parent species be, genetically, to produce this effect? The accompanying table (Moyle et al. 2004) lists the proportion of pollen grains that are sterile in hybrid offspring of crosses between pairs of species of Silene (bladder campions). Also listed is the genetic difference between the pair of species, as measured by DNA sequence divergence. Assume that different species pairs are independent.

a. We would like to predict the proportion of hybrid pollen that is sterile (Y) from the genetic distance between the species (X) . Since the response variable is a proportion, what transformation would be your first choice to help meet the assumptions of linear regression?

b. Transform the proportions and then produce a scatter plot of the data. Estimate and draw the regression line.

c. Calculate the 95% confidence interval for the slope of the line.