An online retailer states that the average number of hours its customers are online each day is 4.96. Suppose a random sample of size 15 of the company's customers is selected and the average number of hours that they are online each day is measured. The sample results are shown in the accompanying table. Complete parts a and b. 2.46 4.86 3.07 3.27 5.28 4.52 8.65 7.26 2.72 6.03 8.04 5.42 2.79 2.39 3.48 a. Based on the sample of 15 customers, how much sampling error exists? The sampling error for the given sample is (Round to four decimal places as needed.)