In an air pollution study performed at the experiment station, the following amount of suspended benzene-soluble organic matter. (in micrograms per cubic meter) was obtained for the 8 different samples of air:
2.2 1.8 3.1 2.0 2.4 2.0 2.1 1.2
Assuming that the population sampled is normal, construct a 95 percent confidence interval for the corresponding true mean.