Contamination from a plant's discharge. Refer to the U.S. Army Corps of Engineers data (Example 1.5, p. 14 ) on fish contaminated from the toxic discharges of a chemical plant located on the banks of the Tennessee River in Alabama. Recall that the engineers measured the length (in centimeters), weight (in grams), and DDT level (in parts per million) for 144 captured fish. In addition, the number of miles upstream from the river was recorded. The data are saved in the file. (The first and last five observations are shown in the table on the next page.)
a. Fit the first-order model. E (y) = β0 + β1 x1 + β2x2 + β3x3, to the data. where y = DDT level. x1 = mile, x2 = length, and x3 = weight. Report the least squares prediction equation.
Data for Exercise 12.18
b. Find the estimate of the standard deviation of c: for the model and give a practical interpretation of its value.
c. Conduct a test of the global utility of the model. Use α =.05.
d. Do the data provide sufficient evidence to conclude that DDT level increases as length increases? Report the observed significance level of the test and reach a conclusion using α =.05.
e. Find and interpret a 95% confidence interval for β3.
Want to see the full answer?
Check out a sample textbook solutionChapter 12 Solutions
Statistics for Business and Economics (13th Edition)
- Determine the maximum and minimum permissible wall thickness of the steel sleeve shown in Figure 29-15.All dimensions are in millimeters.arrow_forwardUrban Travel Times Population of cities and driving times are related, as shown in the accompanying table, which shows the 1960 population N, in thousands, for several cities, together with the average time T, in minutes, sent by residents driving to work. City Population N Driving time T Los Angeles 6489 16.8 Pittsburgh 1804 12.6 Washington 1808 14.3 Hutchinson 38 6.1 Nashville 347 10.8 Tallahassee 48 7.3 An analysis of these data, along with data from 17 other cities in the United States and Canada, led to a power model of average driving time as a function of population. a Construct a power model of driving time in minutes as a function of population measured in thousands b Is average driving time in Pittsburgh more or less than would be expected from its population? c If you wish to move to a smaller city to reduce your average driving time to work by 25, how much smaller should the city be?arrow_forward
- Functions and Change: A Modeling Approach to Coll...AlgebraISBN:9781337111348Author:Bruce Crauder, Benny Evans, Alan NoellPublisher:Cengage LearningAlgebra: Structure And Method, Book 1AlgebraISBN:9780395977224Author:Richard G. Brown, Mary P. Dolciani, Robert H. Sorgenfrey, William L. ColePublisher:McDougal LittellMathematics For Machine TechnologyAdvanced MathISBN:9781337798310Author:Peterson, John.Publisher:Cengage Learning,
- Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill