The population mean waiting time to check out in a supermarket was 10.73 minutes. Recently, in effort to reduce the waiting time, the supermarket has introduced a new checkout system in which there is a single waiting line with multiple checkout servers. After the system has been used for a month, a random sample of 100 customers is selected, and the mean waiting time to check out is 9.52 minutes, with a sample standard deviation of 5.8 minutes. (a) Find the point estimate for the population mean waiting time to check out after the new checkout system is used. (b) Construct a 95% confidence interval estimate for the population mean waiting time to check out after the new checkout system is used. (C) Based on the result in part (b), can the supermarket claim that the new checkout system has reduced the waiting time? (d) The 100 customers are further asked about their satisfactory level towards the new checkout system. Among these 100 customers, 48 respond "good", 30 respond "acceptable", and 22 respond "bad". (1) Find the point estimate for the population proportion of customers "not feeling bad to the new checkout system. (ii) Construct a 90% confidence interval estimate for the population proportion of customers "not feeling bad" to the new checkout system.