In: Statistics and Probability
An article reported that for a sample of 54 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 165.57.
(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.(Which of these are the right statement.)
We are 95% confident that the true population mean lies below this interval
. We are 95% confident that this interval does not contain the true population mean.
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.
(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 58 ppm for a confidence
level of 95%? (Round your answer up to the nearest whole
number.)
Kitchens: |