Which of the following represents a proportional function? A. the amount of money on a gift card, if the original amount is $200 and $50 is spent once a week for 4 weeks

B. the amount of money charged for a hotel room, if the cost is $86 per day

C. the amount of money that is charged for a cleaning service, if the cost is $25 per visit, plus $15 for each hour of work

D. the savings in a bank account, if $100 is initially deposited and $25 is deposited each week afterwards

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.