1. A study of 50 household kitchens with gas stoves yielded a sample mean CO concentration...

 

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1. A study of 50 household kitchens with gas stoves yielded a sample mean CO concentration of 654.16 ppm with a sample standard deviation of 164.43 ppm. (a) Calculate and interpret a 95% confidence interval for the true average CO concentration in the population of all homes with gas stoves from which these 50 kitchens were selected. (b) Suppose that the researchers had made an advance guess that the actual standard deviation was 175 before collecting data. What sample size should they have chosen to create a 95% interval of width 50 ppm? 1. A study of 50 household kitchens with gas stoves yielded a sample mean CO concentration of 654.16 ppm with a sample standard deviation of 164.43 ppm. (a) Calculate and interpret a 95% confidence interval for the true average CO concentration in the population of all homes with gas stoves from which these 50 kitchens were selected. (b) Suppose that the researchers had made an advance guess that the actual standard deviation was 175 before collecting data. What sample size should they have chosen to create a 95% interval of width 50 ppm?