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Answer:
The 95% confidence interval for the mean number of words a third grader can read per minute is (23.8, 24.4).
Step-by-step explanation:
We have to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Z-table as such z has a p-value of .
That is z with a p-value of , so Z = 1.96.
Now, find the margin of error M as such
In which is the standard deviation of the population and n is the size of the sample.
The lower end of the interval is the sample mean subtracted by M. So it is 24.1 - 0.3 = 23.8
The upper end of the interval is the sample mean added to M. So it is 24.1 + 0.3 = 24.4.
The 95% confidence interval for the mean number of words a third grader can read per minute is (23.8, 24.4).