A Internet provider has implemented a new process for handling customer complaints. Based on a review of customer complaint data for the past 2 years, the mean time for handling a customer complain was 27 minutes. Three months after implementing the plan, a random sample of the records of 50 customers who had complaints produced the following response times. Use the 50 data values to determine if the new process has reduced the mean time to handle customer complaints.

a. Estimate the mean time for handling a customer complaint under the new ­process using a 95% confidence interval.
b. Is there substantial evidence (a = .05) that the new process has reduced the mean time to handle a customer complaint?
c. What is the population about which inferences from these data can be made?

323 269 254 32.9 27.7 32.2 248 205 304 21.3 25.9 27.1 19.2 28.4 180 3.1 311 219 33.4 24.3 25.5 29.6 32.7 213 318 27.6 174 26.9 18.9 28.6 235 216 20.1 309 26.8 28.7 24.6 215 219 28.3 24.1 28.9 29.8 27.1 23.8 25.3 30.7 27.2 190 300