Question
In: Statistics and Probability
A college admissions director wishes to estimate the mean age of all students currently enrolled. In...
A college admissions director wishes to estimate the mean age of all students currently enrolled. In a random sample of 81 students, the mean age is found to be 20.51 years. From past studies, the standard deviation of the population is known to be 2 years, and the population is normally distributed. Construct a 99% confidence interval of the population mean age. (Round off final answers to two decimal places, if appropriate. Do not round off numbers taken directly from tables).
Solutions
Expert Solution
Solution :
Given that,
sample size = n = 81
Degrees of freedom = df = n - 1 = 81 - 1 = 80
t
/2,df = 2.639
Margin of error = E = t/2,df
* (s /
= 2.639 * (2 /
Margin of error = E = 0.59
The 99% confidence interval estimate of the population mean is,
- E < 
<
+ E
20.51 - 0.59 <
< 20.51 + 0.59
19.92 <
< 21.10
A 99% confidence interval of the population mean: (19.92 , 21.10)
orchestra answered 2 years agoRelated Solutions
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