The amount of PCBs (polychlorinated biphenyls) was measured in 40 samples of soil that were treated with contaminated sludge. The following summary statistics were obtained.
 = 3.56 s = .5 ppm
(a) Obtain a 95% confidence interval for the population mean μ, amount of PCBs in the soil. Answer parts (b), (c), and (d) Yes, No, or Cannot tell. Explain your answer.
(b) Does the sample mean PCB content lie in your interval obtained in part (a)?
(c) Does the population mean PCB content lie in your interval obtained in part (a)?
(d) Is it likely that 95% of the data lie in your interval obtained in part (a)?