An article reported that for a sample of 55 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. (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.) 330.31 Incorrect: Your answer is incorrect. , 978.01 Incorrect: Your answer is incorrect. ppm Interpret the resulting 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. We are 95% confident that the true population mean lies below this interval. Correct: Your answer is correct. (b) Suppose the investigators had made a rough guess of 169 for the value of s before collecting data. What sample size would be necessary to obtain an interval width of 51 ppm for a confidence level of 95%