5.13 To draw the boxplot of log(pres) versus Source, and the scatterplot of log(pres) versus bp, using a different symbol for Source, we need (assuming that we have set up the combined.data correctly):

Boxplot(log(pres)~Source, data=combined.data)
scatterplot(log(pres) ~ bp | Source, data=combined.data, smooth=FALSE, boxplots=FALSE)