1) When people smoke, the nicotine they absorb is converted to cotinine, which can be measured through blood tests. A random sample of 40 smokers has a mean cotinine level of 172.5 ng/ml. Assuming that= 119.5 ng.ml, test the claim that the mean cotinine level of all smokers is equal to 200.0 ng/ml. Use a 0.05 significance level.

2) Listed below are the measured amounts of lead (in micrograms per cubic meter) in the air. The measurements shown below were recorded at Building 5 of the World Trade Center site on different days following Sept 11, 2001. After the collapse of the two World Trade Center buildings, there was considerable concern about the quality of the air. Use a 0.05 significance level to test the claim that the sample is from a population with a mean greater than the EPA standard of 1.5. Is there anything about this data set suggesting that the assumption of a normally distributed population might not be valid? Explain.

5.40

1.10

0.42

0.73

0.48

1.10