A school administrator wants to see if there is a difference in the number of students per class for the Portland Public School district (Group 1) compared to the Beaverton School district (Group 2). Let 441 be the average number of students per class for the Portland Public School district. Let ₂ be the average number of students per class for the Beaverton School district. Assume the populations are normally distributed. A random sample of 25 Portland classes found a mean of 38 students per class with a standard deviation of 3. A random sample of 28 Beaverton classes found a mean of 35 students per class with a standard deviation of 4. a. Find a 95% confidence interval for the difference of the means. Use Excel Two Means Calculator found in the Course and round answers to 2 decimal places.

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A school administrator wants to see if there is a difference in the number of students per class for the
Portland Public School district (Group 1) compared to the Beaverton School district (Group 2).
Let be the average number of students per class for the Portland Public School district.
Let ₂ be the average number of students per class for the Beaverton School district. Assume the
populations are normally distributed.
A random sample of 25 Portland classes found a mean of 38 students per class with a standard deviation of
3.
A random sample of 28 Beaverton classes found a mean of 35 students per class with a standard deviation
of 4.
a. Find a 95% confidence interval for the difference of the means. Use Excel Two Means Calculator
found in the Course and round answers to 2 decimal places.
<1-1₂<
b. Select the correct conclusion based on the above confidence interval.
Since the above confidence interval gives only negative values, we have 95% confident that
the average number of students per class for the Portland Public School district is smaller
than that for the Beaverton School district.
O Since the above confidence interval gives only positive values, we have 95% confident that
the average number of students per class for the Portland Public School district is higher than
that for the Beaverton School district.
Since the above confidence interval contains zero, with 95% confident, it is plausible that the
average number of students per class for the Portland Public School district is same as that
for the Beaverton School district.
c. Using these data, at significance level of 0.05, if you were testing whether there is a difference in
the average number of students per class for the Portland Public School district compared to the
Beaverton School district,
then the conclusion would be
O different from above
same as above
because we used Select an answer confidence level and significance level.
Transcribed Image Text:A school administrator wants to see if there is a difference in the number of students per class for the Portland Public School district (Group 1) compared to the Beaverton School district (Group 2). Let be the average number of students per class for the Portland Public School district. Let ₂ be the average number of students per class for the Beaverton School district. Assume the populations are normally distributed. A random sample of 25 Portland classes found a mean of 38 students per class with a standard deviation of 3. A random sample of 28 Beaverton classes found a mean of 35 students per class with a standard deviation of 4. a. Find a 95% confidence interval for the difference of the means. Use Excel Two Means Calculator found in the Course and round answers to 2 decimal places. <1-1₂< b. Select the correct conclusion based on the above confidence interval. Since the above confidence interval gives only negative values, we have 95% confident that the average number of students per class for the Portland Public School district is smaller than that for the Beaverton School district. O Since the above confidence interval gives only positive values, we have 95% confident that the average number of students per class for the Portland Public School district is higher than that for the Beaverton School district. Since the above confidence interval contains zero, with 95% confident, it is plausible that the average number of students per class for the Portland Public School district is same as that for the Beaverton School district. c. Using these data, at significance level of 0.05, if you were testing whether there is a difference in the average number of students per class for the Portland Public School district compared to the Beaverton School district, then the conclusion would be O different from above same as above because we used Select an answer confidence level and significance level.
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