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Answer:
The 80% confidence interval for the population proportion of tenth graders reading at or below the eighth grade level is (0.149, 0.207).
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
Suppose a sample of 292 tenth graders is drawn. Of the students sampled, 240 read above the eighth grade level.
So 292 - 240 = 52 read below or at eight grade level, and that
80% confidence level
So , z is the value of Z that has a pvalue of
, so
.
The lower limit of this interval is:
The upper limit of this interval is:
The 80% confidence interval for the population proportion of tenth graders reading at or below the eighth grade level is (0.149, 0.207).