Waiting at an ER. A hospital administrator hoping to improve wait times decides to estimate the average emergency room waiting time at her hospital. She collects a simple random sample of 64 patients and determines the time (in minutes) between when they checked in to the ER until they were first seen by a doctor. A 95% confidence interval based on this sample is (128 minutes, 147 minutes), which is based on the normal model for the mean. Determine whether the following statements are true or false, and explain your reasoning.
(a) We are 95% confident that the average waiting time of these 64 emergency room patients is between 128 and 147 minutes.
(b) We are 95% confident that the average waiting time of all patients at this hospital’s emergency room is between 128 and 147 minutes.
(c) 95% of random samples have a sample mean between 128 and 147 minutes.
(d) A 99% confidence interval would be narrower than the 95% confidence interval since we need to be more sure of our estimate.
(e) The margin of error is 9.5 and the sample mean is 137.5.
(f) In order to decrease the margin of error of a 95% confidence interval to half of what it is now, we would need to double the sample size.