An article reported that for a sample of 46 kitchens with gas cooking appliances monitored during a one-week period, the sample mean CO2 level (ppm) was 654.16, and the sample standard deviation was 165.06.
(a) Calculate and interpret a 95% (two-sided) confidence interval for true average CO2 level in the population of all homes from which the sample was selected. (Round your answers to two decimal places.)
,
ppm
Interpret the resulting interval.
We are 95% confident that the true population mean lies below this interval.We are 95% confident that the true population mean lies above this interval. We are 95% confident that this interval contains the true population mean.We are 95% confident that this interval does not contain the true population mean.
(b) Suppose the investigators had made a rough guess of 181 for the value of s before collecting data. What sample size would be necessary to obtain an interval width of 54 ppm for a confidence level of 95%? (Round your answer up to the nearest whole number.)
kitchens
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