Mary Flindt, a Marketing Director with Epsilon Airlines, is assessing the relative importance of the "total flight" experience. An item on a survey questionnaire distributed to 100 of Epsilon's customers asked them to rate the importance of "on-time arrival" on a scale of 1 to 10 (with 1 meaning "not important" and 10 meaning "highly important"). Her staff assembled the following statistics from the responses. If Mary concludes that the average rate of "on-time arrival" for all customers is 9.1, she is using .