Refer to the Marine Mammal Science (April 2010) study of whales entangled in fishing gear, Exercise 10.32 (p. 524). Data collected for a sample of 207 entanglements in the East Sea of Korea were used to model the length (y) of an entangled whale (in meters). Two independent variables used to predict whale length were water depth of the entanglement (x1, in meters) and distance of the entanglement from land (x2, in miles).
a. Give the equation of a first-order model for length (y) as a function of the two independent variables.
b. The researchers theorize that the length of an entangled whale will increase linearly as the water depth increases, for entanglements that are a fixed distance from land. Explain how to use the model, part a, to test this theory.