The (incomplete) data below were collected in southern Florida between 1968 and 1972 to test a hypothesis that massive injection of silver iodide into cumulus clouds can lead to increased rainfall. Rainfall (acre-feet) from unseeded days (n = 26) 1202.6, 830.1, 4.9, 1.0 Rainfall (acre-feet) from seeded days (n = 26) 2745.6, 1697.1, 7.7, 4.1 On each of 52 days that were deemed suitable for cloud seeding, a random mechanism was used to decide whether to seed the target cloud on that day or to leave it unseeded as a control. An airplane flew through the cloud in both cases since the pilot and the experimenters were themselves unaware of whether on any particular day the seeding mechanism in the plane was loaded or not. Precipitation was measured as the total rain volume falling from the cloud base following the airplane run, as measured by radar. (a) Is this study an observational study or a randomized experiment? Explain your answer. (b) Who are the subjects in this case? (c) What is the explanatory variable in this case? What is the response variable? Identify each as being qualitative or quantitative. (d) What are the treatments in this case? (e) Why were the pilots and the experimenters blinded?