Refer to the accompanying data display that results from a sample of airport data speeds in Mbps. Complete parts (a) through (c) TInterval below. (13.046,22.15) Click the icon to view a t distribution table. x = 17.598 Sx = 16.01712719 n = 50 a. What is the number of degrees of freedom that should be used for finding the critical value to / 2? af = (Type a whole number.) b. Find the critical value to / 2 corresponding to a 95% confidence level. ta/2 = (Round to two decimal places as needed.) c. Give a brief general description of the number of degrees of freedom. O A. The number of degrees of freedom for a collection of sample data is the number of sample values that are determined after certain restrictions have been imposed on all data values. O B. The number of degrees of freedom for a collection of sample data is the total number of sample values. O C. The number of degrees of freedom for a collection of sample data is the number of unique, non-repeated sample values. O D. The number of degrees of freedom for a collection of sample data is the number of sample values that can vary after certain restrictions have been imposed on all data values