A 1980 study was conducted whose purpose was to compare theindoor air quality in offices
where smoking was permitted with that in offices where smoking wasnot permitted. Measurements were made
of carbon monoxide (CO) at 1:20 p.m. in 36 work areas where smokingwas permitted and 36 work areas where
smoking was not permitted. In the sample where smoking waspermitted, the mean CO = 11.6 parts per million
(ppm) and the standard deviation CO = 7.3 ppm. In the sample wheresmoking was not permitted, the mean CO
= 6.9 ppm and the standard deviation CO = 2.7 ppm. Test for whetheror not the mean CO is significantly (α =
0.05) different in the two types of working environments.
(a) What is the null hypothesis for this problem? What is thealternative hypothesis?
(b) For this problem, would you perform a one- or two-tailed test?Explain how you reached that decision.
(c) Determine which procedure (you have learned five situations) isthe appropriate statistical test to use, with
a clear explanation for your choice.
(d) Using your calculator, test the null hypothesis and presentyour results. Show all your work.
(e) Using statistical language (“statistic-ese”), state yourconclusion and your reasoning for reaching this
conclusion. Then restate your conclusion, this time in Englishinstead of “statistic-ese,” without including
statistical symbols or the term hypothesis. (What is the answer tothe researcher’s question?)
(f) State, based on your conclusion, whether you may have committeda Type I error or a Type II error, and
what that means.