A class of fourth graders decides to split into groups based on the first letter of their last names. then, they choose students from each group. what type of sampling is used? A. Quota sampling

B. Volunteer sampling

C. Purposive sampling

D. Convenience sampling

David and alton are training for a race. they spend 35 minutes stretching and then go on a 5 mile practice run. david runs at a pace of 7 min/mile. alton runs at a pace of 8 min/mile. write an equation for each runner that shows the total length of their workout. then solve each equation showing your work