Dissolved organic compound in lakes. The level of dissolved oxygen in the surface water of a lake is vital to maintaining the lake’s ecosystem. Environmentalists from the University of Wisconsin monitored the dissolved oxygen levels over time for a sample of 25 lakes in the state (Aquatic Biology, May 2010). To ensure a representative sample, the environmentalists focused on several LO9 lake characteristics, including dissolved organic compound

(DOC). The DOC data (measured in grams per cubic meters)

for the 25 lakes are listed in the table on p. 428. The population of Wisconsin lakes has a mean DOC value of 15 grams>m3. Use a hypothesis test (at a = .10) to make an inference about whether the sample is representative of all Wisconsin lakes for the characteristic dissolved organic compound.

Lake DOC Allequash 9.6 Big Muskellunge 4.5 Brown 13.2 Crampton 4.1 Cranberry Bog 22.6 Crystal 2.7 EastLong 14.7 Helmet 3.5 Hiawatha 13.6 Hummingbird 19.8 Kickapoo 14.3 Little Arbor Vitae 56.9 Mary 25.1 Muskellunge 18.4 Northgate Bog 2.7 Paul 4.2 Peter 30.2 Plum 10.3 Reddington Bog 17.6 Sparkling 2.4 Tenderfoot 17.3 Trout Bog 38.8 Trout Lake 3.0 Ward 5.8 West Long 7.6