As part of its eco-friendly campaign, a company has asked for your advice whethe
ID: 3178493 • Letter: A
Question
As part of its eco-friendly campaign, a company has asked for your advice whether installing a wind turbine will generate enough electricity to be cost effective. To produce enough electricity, the average wind speed needs to be least 19 mph. Based on historical data from the past 5 years, 43 days were randomly chosen and their wind speed measurements were written down. This resulted in an average wind speed of 20 mph with a standard error of 0.6252 mph. A histogram of these wind speeds yielded a right-skewed shape.
a) Are the conditions met for constructing a confidence interval? (Check all that apply.)
None of the conditions are met.
The Nearly Normal condition is met.
It is reasonable to assume that weather conditions on the various days were independent of each other.
The days were randomly chosen.
(b) Find the 90% confidence interval for the true average wind speed. (Use 4 decimal places)
Explanation / Answer
The Nearly Normal condition is met.
The days were randomly chosen.
It is reasonable to assume that weather conditions on the various days were independent of each other.
b) for 90% CI, z=1.64485
hence confidence interval =mean +/- z*std error =18.9716 ; 21.0284
from t distribution
for 42 degree of freedom . at 90% CI ,t=2.018
hence confidence interval =mean +/- t*std error =18.7383 ; 21.2617
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