In a certain suburb of Montréal, residents have expressed their worries about the quality of the air. Of particular concern is the concentration (in μg/m3) of particulate matter smaller than 2.5 μm in size (PM2.5). The environmental standard is a PM2.5 concentration of 15 μg/m3 or less. 9-a) To conduct this study, Thomas installs 25 PM2.5 detectors at different locations in the suburban area. Each detector will provide one reading of PM2.5 concentration at a giv
In a certain suburb of Montréal, residents have expressed their worries about the quality of the air. Of particular concern is the concentration (in μg/m3) of particulate matter smaller than 2.5 μm in size (PM2.5). The environmental standard is a PM2.5 concentration of 15 μg/m3 or less.
9-a) To conduct this study, Thomas installs 25 PM2.5 detectors at different locations in the suburban area. Each detector will provide one reading of PM2.5 concentration at a given time. With 25 detectors, what is the
9-b) Thomas is interested to purchase a new and cheaper instrument to measure PM2.5 concentration. He is worried, however, that the precision of the new instrument may be lower than that of the current one. To be acceptable, the standard deviation of measurements made with the new instrument should not exceed 5 μg/m3. To assess whether he could reliably usethe new instrument, Thomas makes 10 readings of an air sample with known concentration of PM2.5. From the data, he calculates a sample standard deviation of 7 μg/m3. Is the variability in the 10 readings made with the new instrument acceptable? Use α = 0.05.
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