Carp diet study. Fisheries Science (February 1995) reported on a study of the variables that affect endogenous nitrogen excretion (ENE) in carp raised in Japan. Carp were divided into groups of 2-15 fish, each according to body weight and each group placed in a separate tank.
The carp were then fed a proteinfree diet three times daily for a period of 20 days. One day after terminating the feeding experiment, the amount of ENE in each tank was measured. The table gives the mean body weight (in grams) and ENE amount (in milligrams per 100 grams of body weight per day) for each carp group
(a) Graph the data in a scatterplot. Do you detect a pattern?
(b) The quadratic model E(y) = β0 + β1x + β2x2 was fit to the data using MINITAB. The MINITAB printout is displayed. Conduct the test H0: β2 = 0 against Ha: β2 = 0 using α = .10. Give the conclusion in the words of the problem.