In: Statistics and Probability
Listed below are student evaluation ratings of courses, where a rating of 5 is for "excellent." The ratings were obtained at one university in a state. Construct a confidence interval using a 95% confidence level. What does the confidence interval tell about the population of all college students in the state? 3.8, 2.9, 3.9, 4.7, 2.9, 4.3, 3.6, 4.8, 4.6, 4.2, 4.1, 3.8, 3.2, 4.1, 3.8 What is the confidence interval for the population mean u?
Solution :
The 95% confidence interval for population mean is given as follows :
Where, x̄ is sample mean, s is sample standard deviation, n is sample size and t(0.05/2, n-1) is critical t-value to construct the 95% confidence interval.
We have, n = 15
Using t-table we get, t(0.05/2, 15-1) = 2.145
Hence, 95% confidence interval is for the population mean is,
The 95% confidence interval for population mean is (3.586, 4.24).
Interpretation : We are 95% confident that true value of population mean rating of all college students in the state, lies within the calculated 95% confidence interval.
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