Chris would like to conduct a study on the effectiveness of a new substance-abuse treatment program. He has a sample of participants go through the program and he uses as a comparison group people who did not volunteer for the program but were eligible. Chris has used a(n) design for his study.

a. nonequivalent group
b. interrupted time-series
c. pretest-posttest control-group
d. Solomon four-group

The correct answer is letter "A": nonequivalent group.

Explanation:

While conducting studies, nonequivalent groups are those where the target audience is not selected randomly. Instead, the participants are chosen generating another group represented by all those individuals who match the research criteria but, because of a reason, were not selected.

There are different types of nonequivalent groups such as posttest only nonequivalent groups or pretest-posttest nonequivalent groups, for instance.

answer; burned it;

answer: marginal utility of the fourth brownie is 0.

explanation: marginal utility is the addtional utility gained from the consumption of one more unit of a good. it is given by,

so, marginal utility at the 4th unit will be given by

since, the values are not given here, you can simply find marginal utility at fourth unit by subtracting total utility at 3rd unit from total utility at 4th unit.