C. The way the sample was chosen may overrepresent or underrepresent students taking certain language classes.
The samples he chose may not be a representative sample because the number of students per foreign language class may not be the same. Since classes have different numbers of students, one may have a very large number of students while another may have only a few. Taking equal number of students per class is not a representative sample because it doesn't represent the students correctly.
Answer:
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Step-by-step explanation:
Answer:
First find the hypotenuse of the small triangle then use that value as the base of the upper triangle. Evaluate the equation formed with the “x"
Answer: 1.303639
Step-by-step explanation:
The t-score for a level of confidence
is given by :_
, where df is the degree of freedom and
is the significance level.
Given : Level of significance : 
Then , significance level : 
Sample size : 
Then , the degree of freedom for t-distribution: 
Using the normal t-distribution table, we have

Thus, the t-score should be used to find the 80% confidence interval for the population mean =1.303639