Cotinine Levels of Smokers. Find and interpret a confidence interval for the mean.
Cotinine Levels of Smokers When people smoke, the nicotine they absorb is converted to cotinine, which can be measured. A sample of 40 smokers has a mean cotinine level of 172.5. Assume that the population standard deviation is known to be 119.5, find a 90% confidence interval estimate of the mean cotinine level of all smoker