Respuesta :
Answer:
The 95% confidence interval [tex] 81.852 < \mu < 280.098 [/tex]
Step-by-step explanation:
From the question we are told that
The sample mean is [tex]\= x = 180.975[/tex]
The standard deviation is [tex]\sigma = 143.042[/tex]
The sample size is n = 8
Given that the confidence level is 95% then the level of significance is
[tex]\alpha =( 100- 95) \%[/tex]
=> [tex]\alpha =0.05[/tex]
Generally from the normal distribution table the critical value of [tex]\frac{\alpha }{2}[/tex] is
[tex]Z_{\frac{\alpha }{2} } = 1.96[/tex]
Generally the margin of error is mathematically represented as
[tex]E = Z_{\frac{\alpha }{2} } * \frac{\sigma }{\sqrt{n} }[/tex]
=> [tex]E = 1.96 * \frac{ 143.042 }{\sqrt{8} }[/tex]
=> [tex]E = 99.123 [/tex]
Generally 95% confidence interval is mathematically represented as
[tex]\= x -E < \mu < \=x +E[/tex]
=> [tex]180.975 -99.123 < p < 180.975 +99.123[/tex]
=> [tex] 81.852 < \mu < 280.098 [/tex]
Using the t-distribution, it is found that the 95% confidence interval for the mean endowment of all the private colleges in the United States assuming a normal distribution for the endowments, in millions of dollars, is (61.39, 300.56).
The information given is:
- Sample mean of [tex]\overline{x} = 180.975[/tex].
- Sample standard deviation of [tex]s = 143.042[/tex]
- Sample size of [tex]n = 8[/tex].
We have the standard deviation for the sample, hence, the t-distribution is used.
The interval is given by:
[tex]\overline{x} \pm t\frac{s}{\sqrt{n}}[/tex]
The critical value for a two-tailed 95% confidence interval with 8 - 1 = 7 df is t = 2.3646.
Then:
[tex]\overline{x} - t\frac{s}{\sqrt{n}} = 180.975 - 2.3646\frac{143.042}{\sqrt{8}} = 61.39[/tex]
[tex]\overline{x} + t\frac{s}{\sqrt{n}} = 180.975 + 2.3646\frac{143.042}{\sqrt{8}} = 300.56[/tex]
The 95% confidence interval for the mean endowment of all the private colleges in the United States assuming a normal distribution for the endowments, in millions of dollars, is (61.39, 300.56).
To learn more about the t-distribution, you can take a look at https://brainly.com/question/25077184
