Scores on final exams in a class have been known to be skewed to the left. A pro

Question

Scores on final exams in a class have been known to be skewed to the left. A professor giving a test wonders if the average score will be above a 70. She grades the first 15 submitted and find an average of 71. Which of the following is true regarding using the one-sample z-methods?

A.She should be cautious in using the sample data to make an inference about all scores on this test since the sample size is less than 30 and the population data may be skewed.

B.She should be cautious in using the sample data to make an inference about all scores on this test since the scores of the first 15 submitted may not be representative of scores of all final exams submitted.

C.both A and B

D.An inference to all scores on this test can be made based on the sample data since the distribution of sample means will be normal

E.An inference to all scores on this test can be made based on the sample data since the sample is representative of the population of all scores on this test.

F.both D and E

Explanation / Answer

She should be cautious because the data is skewed and also the random sampling has not been done.

Hence, both A and B are correct.

Option C is correct.

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