Refer to Exercise 8.88. A report from a testing laboratory

Chapter 10, Problem 74E

(choose chapter or problem)

Problem 74E

Refer to Exercise 8.88. A report from a testing laboratory claims that, for these species of fish, the average LC50 measurement is 6 ppm. Use the data of Exercise 8.88 to determine whether sufficient evidence exists to indicate that the average LC50 measurement is less than 6 ppm. Use α = .05.

Reference

The Environmental Protection Agency (EPA) has collected data on LC50 measurements (concentrations that kill 50% of test animals) for certain chemicals likely to be found in freshwater rivers and lakes. (See Exercise 7.13 for additional details.) For certain species of fish, the LC50 measurements (in parts per million) for DDT in 12 experiments were as follows:

16, 5, 21, 19, 10, 5, 8, 2, 7, 2, 4, 9

Estimate the true mean LC50 for DDT with confidence coefficient .90. Assume that the LC50 measurements have an approximately normal distribution.