Testing and Estimating m with s Unknown Carboxyhemoglobin is formed when hemoglobin is exposed to carbon monoxide. Heavy smokers tend to have a high percentage of carboxyhemoglobin in their blood

(Reference: A Manual of Laboratory and Diagnostic Tests by F. Fischbach). Let x be a random variable representing percentage of carboxyhemoglobin in the blood. For a person who is a regular heavy smoker, x has a distribution that is approximately normal. A random sample of n 5 12 blood tests given to a heavy smoker gave the following results (percentage of carboxyhemoglobin in the blood):

9.1 9.5 10.2 9.8 11.3 12.2 11.6 10.3 8.9 9.7 13.4 9.9

(a) Use a calculator to verify that x < 10.49 and s < 1.36.

(b) A long-term population mean m 5 10% is considered a health risk. However, a long-term population mean above 10% is considered a clinical alert that the person may be asymptomatic. Do the data indicate that the population mean percentage is higher than 10% for this patient? Use a 5 0.05.

(c) Use the given data to fi nd a 99% confi dence interval for m for this patient.