3.60 Removing nitrogen from toxic toxic wastewater Highly toxic wastewater is produced during the manufacturing of dry-spun acrylic fiber. One way to lessen toxicity is to remove the nitrogen from the wastewater. A group of environmental engi neers investigated a promising method for nitro- gen removal, anaerobic ammonium oxidation, and reported the results in the Chemical Engineering Journal (April 2013). A sample of 120 specimens of toxic wastewater were collected and treated with the nitrogen removal method. The amount of nitrogen removed (measured in milligrams per liter) was determined as well as the amount of ammonium (milligrams per liter) used in the removal process. These data (simulated from infor- mation provided in the journal article) are saved in the NITRO file. The data for the first 5 speci- mens are shown below. A simple linear regression analysis, where y = amount of nitrogen removed and x = amount of ammonium used, is also shown in the accompanying SAS printout. (a) Statistically assess the adequacy of the fit of the linear model. Do you recommend using the model for predicting nitrogen amount? (b) On the SAS printout, locate a 95% prediction interval for nitrogen amount when the amount of ammonium used is 100 milligrams per liter. Practically interpret the result. (c) Will a 95% confidence interval for the mean nitrogen amount when the amount of ammo- nium used is 100 milligrams per liter be wider or narrower than the interval, part b? Explain. NITRO (First 5 observations of 120 shown) NITROGEN AMMONIUM 18.87 67.40 17.01 12.49 23.88 61.96 10.45 15.63 36.03 83.66