1:39 26 Ill 61 Problem-solvin... . . . Name: ID Number: Section Code: PROBLEM-SOLVING 1. A random sample of 40 items resulted in a sample mean of 25. The population variance is of = 25. a. What is the standard error of the mean, of ? b. What is the margin of error using a 95% confidence level? c. Compute for a 90% confidence interval for the population mean? d. Compute for a 95% confidence interval for the population mean? e. Compute for a 99% confidence interval for the population mean? 2. The research and development (R & D) head of SM Seaside City wants to estimate the number of customers who enter the mall every three minutes. He randomly samples three-minute intervals and counts the number of arrivals at the mall. He obtained the following data: 68, 42, 51, 57, 56, 80, 45, 39,36, and 79. The R & D head assumes that the number of arrivals is normally distributed. Using these data, the director computes a 95% confidence interval to estimate the average value for all three-minute interval. What interval does he get? E O