The health department is conducting a survey to understand the average amount of time that all the residents in this city spend exercising each week. To gather data, they decide to survey every ninth person entering a major public park on a Saturday. (a) What is the sample for this study? the average amount of exercise time per week of all the ninth residents on that Saturday all the residents in this city all the ninth residents on that Saturday the average amount of exercise time per week of all the residents in this city (b) What type of measurement scale is used? interval nominal ordinal ratio