Egyptian researchers, Kamal et al. (1991), took a sample of 126 police officers subject...

Egyptian researchers, Kamal et al. (1991), took a sample of 126 police officers subject to inhalation of vehicle exhaust in downtown Cairo and found an average blood level concentration of lead equal to 29.2 g/dl. Form a confidence interval for the population difference and test the null hypothesis that there is no difference in the populations.