A study compared paired daytime and nighttime counts of electric eel, peacock eel, and black spotted eel made by the same divers in seven lakes during June 2015. Overall, they counted 126 eels during the day and 291 eels at night. The researchers speculate that eels counted at night were present during the
daytime, but were hidden from view. Biologists should consider that eel behavior and susceptibility to being seen might vary a great deal between daytime and
nighttime, even during the summer. In some lakes, the majority of eels may not be seen during the daytime. Determine whether the study is an observational
study or an experiment. Justify your answer with specific references to the information in the study.

Experimental study, because the divers are catching eels for a sample

Observational study, because the divers are watching the eels only during the day

Experimental study, because the divers are watching the eels during the day and night

Observational study, because the divers are not catching eels for a sample

Unable to determine whether this is an observational study or experiment

Which scenarios are most effectively explored by conducting an experiment? there is more than one correct answer. select all that apply. researchers want to study the effectiveness of a particular drug for treating migraines. they want to know which dosage of the drug yields the best results with the least side effects. to ensure fair results, the researchers want to ensure that participants and dosage administrators do not know which dosage participants receive. a teacher wants to plan a class fieldtrip and quickly determine where students prefer to go for the class fieldtrip. a car mechanic wants to know which of two engine brands makes better-performing engines. he wants to test the engines in identical situations and rate their performance in a way that can be fairly measured. a chemist studies the properties of a metal compound. she wants to know how the sample size of the metal affects its ability to conduct electricity. she wants to conduct the research in a controlled environment to minimize bias. a realty company wants to know the average income of its clients. the company wants to gather data income from current clients.