Data on the content of milk from Canadian cows of five different breeds and two different ages can be found in the butterfat dataset.

a. Make appropriate plots of the data.
b. Determine whether there is an interaction between breed and age.
c. Determine whether there is statistically significant difference between breeds and also ages.
d. Present regression diagnostics for your chosen model and comment whether the assumptions have been met.
e. Is the best breed in terms of butterfat content clearly superior to the second best breed