# Question: An environmental impact study was performed in a small state

An environmental impact study was performed in a small state to determine the effectiveness of scrubbers on the amount of pollution coming from the cooling towers of a chemical plant. The amounts of pollution (in ppm) detected from the cooling towers before and after the scrubbers were installed are given below for 23 cooling towers.

Suppose a larger study is planned for a state with a more extreme pollution problem.

a. How many chemical plant cooling towers need to be measured if we want a probability of .90 of detecting a mean reduction in pollution of 10 ppm due to installing the scrubbers using an α = .01 test?

b. What assumptions did you make in part (a) in order to compute the sample size?

Suppose a larger study is planned for a state with a more extreme pollution problem.

a. How many chemical plant cooling towers need to be measured if we want a probability of .90 of detecting a mean reduction in pollution of 10 ppm due to installing the scrubbers using an α = .01 test?

b. What assumptions did you make in part (a) in order to compute the sample size?

**View Solution:**## Answer to relevant Questions

Long-distance runners have contended that moderate exposure to ozone increases lung capacity. To investigate this possibility, a researcher exposed 12 rats to ozone at the rate of two parts per million for a period of 30 ...Refer to Exercise 6.46. The researchers also examined the effect of depth on population abundance. In exercise a. Plot the four data sets using side-by-side boxplots to demonstrate the effect of depth on population ...To assess whether degreed nurses received a more comprehensive training than registered nurses, a study was designed to compare the two groups. The state nursing licensing board randomly selected 50 nurses from each group ...Refer to Exercise 6.60. In exercise Instead of conducting a statistical test, use the sample data to answer the question, what is the difference in mean flare illuminations for the two mixtures? The number of households currently receiving a daily newspaper has decreased over the last 10 years, and many people state they obtain information about current events through television news and the Internet. To test ...Post your question