SOLUTION: Cecilia wants to know what percent of the seventh-grade students at her school are bilingual. She surveyed a random sample of seventh and eighth grade students at her school. Which

Question 1039651: Cecilia wants to know what percent of the seventh-grade students at her school are bilingual. She surveyed a random sample of seventh and eighth grade students at her school. Which of the following best explains why this sample is or is not a representative of the population Cecilia wants to study?
A. The sample is representative, because it is a random sample.
B. The sample is not representative because it is a random sample.
C. The sample is not representative because it included eight grade students.
D. The sample isn't represtative, because it does not include every seventh grade student in the school.
A: I think the answer is A.
B. It's not b because random samples are representative.
C. The eighth grade students dont interfere with her survey.
D. I think it can be D, however I am more confident in A.
Am I correct? If so why not
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!

Of course, the presence of 8th-grade students' responses skew the survey. If you wanted to know what percentage of 25 to 30-year-old women participate in Pilates, would you include data from a group of 40-year-old men? Every participant in a survey must be a member of the group about which you want to draw conclusions. That's why survey instruments gather demographic data as well as data that is the subject of the study.

So, A is wrong. B is wrong for the reason you stated. C is right for the reasons I gave. And D is wrong because not getting a response from everyone in the population is the whole point of random sampling. What if Cecilia wanted to study all seventh-grade students in the state she lives in? There are situations where it is impossible, or at least prohibitively expensive to survey every member of a population under study.

John

My calculator said it, I believe it, that settles it

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