Chlorophyll in Florida Everglades water. The Organic Geochemistry Group at Florida Atlantic University studied the photosynthetic pigments in the waters of the Florida Everglades (Florida Scientist, Fall 2004). The researchers measured the amount of chlorophyll in a liter of water collected from the Florida Bay using each of two methods: spectrophotometry (y) and high-performance liquid chromatography (x). 

a. Write a first-order (straight-line) model for E(y). Inter- pret the betas in the model. 

b. Theoretically, if there is no chlorophyll in the water specimen, then both x = 0 and y = 0. Rewrite the model, part a, assuming that the line will go through the origin, (0,0). 

c. Write a second-order (quadratic) model for E(y). 

d. What is the expected sign of B2 in the model, part c, if theory indicates that as the high-performance liquid chromatography measurement (x) increases, the spec- trophotometry measurement (y) will increase at a de- creasing rate?