Bromeliads are tropical flowering plants. Many are epiphytes that attach to trees and obtain moisture and nutrients from air and rain. Their leaf bases form cups that collect water and are home to the larvae of many insects. As a preliminary to a study of changes in the nutrient cycle, Jacqueline Ngai and Diane Srivastava examined the effects of adding nitrogen, phosphorus, or both to the cups. They randomly assigned eight bromeliads growing in Costa Rica to each of four treatment groups, including an unfertilized control group. A monkey destroyed one of the plants in the control group, leaving seven bromeliads in that group. Here are the numbers of new leaves on each plant over the seven months following fertilization: Nitrogen Phosphorus Both Neither
15 15 14 14
14 17 18 19
18 13 14 11
16 13 15 16
14 14 15 13
11 17 1 14
15 13 12 15

Required:
a. Give the degrees of freedom for the F statistic.
b. Find the F-statistic.
c. Find the associated P-value.