1. Researchers wanted to see how two new varieties of fish food compare to a commonly used food. They took 180 similar fish and assigned them randomly to three different tanks. The fish in tank 1 received one variety of new food, the fish in tank 2 received the other variety of new food, and the fish in tank 3 received the commonly used food. The growth and health of the fish was measured over a period of 4 weeks. a. Was this an experiment or an observational study? Explain briefly. b. For each of the principles of experimental design (Control, Randomize, Replicate, and Block), say whether it is present in this scenario. Explain briefly. c. Can this study be done in a double-blind way? Explain. 2. A community college wants to collect opinions from its students on campus transportation issues, such as bus service and parking. Of the total 5000 students in the college, 500 live on campus, 1000 don't regularly come to campus during the day (taking only evening or online classes), and the remaining 3500 have classes on campus at least one day each week. a. Why might the college want to use a stratified random sample? b. The college asks you to select a stratified random sample of 200 students. How many of each type of student will you select? 4. On March 30, 2023, Pew Research Organization released the results of a survey. They asked a group of 10,701 U. S. adults their opinion of the Central Intelligence Agency (CIA). The possible responses were Very Favorable, Somewhat Favorable, Very Unfavorable, Somewhat Unfavorable, Not Sure, and No answer. a. Clearly identify the population in this situation. b. Clearly identify the sample in this situation. c. Clearly identify one population parameter of interest in this situation.