An article reported that for a sample of 40 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 165.23.
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
(b) suppose the investigators had made a rough guess of 167 for the value of s before collecting data. what sample size would be necessary to obtain an interval width of 57ppm for a confidence level of 95%? (round your answer up to the nearest whole number.)
= kitchens