A 90% confidence interval for the proportion of cell phone owners aged 18 - 24 who have an Android phone is 0.503 < p < 0.397.
In the given question,
We have to construct a 90% confidence interval for the proportion of cell phone owners aged 18 - 24 who have an Android phone.
A 90% confidence interval for the proportion of cell phone owners aged 18 - 24 who have an Android phone is
..............< p <...............
We have to construct the 90% confidence interval.
From the given question we know that among 240 cell phone owners aged 18 - 24 surveyed, 108 said their phone was an android phone.
So the total number of cell phone owners aged 18 - 24 is 240.
So n=240
From them 108 have an android phone.
So x=108
Estimation of sample proportion([tex]\hat p[/tex]) = x/n
Now putting the value
Estimation of sample proportion([tex]\hat p[/tex]) = 108/240
Estimation of sample proportion([tex]\hat p[/tex]) = 0.45
Now the construct a 90% confidence interval for the proportion of cell phone owners aged 18 - 24 who have an Android phone
C.I. = [tex](\hat p \pm z_{\alpha /2}\sqrt\frac{\hat p(1-\hat p)}{n}})[/tex]
As we know that
[tex]\hat p=0.45[/tex]
Now finding the value of [tex]z_{\alpha /2}[/tex]
We have to find the 90% confidence interval. We can write 90% as 90/100 = 0.90
So [tex]\alpha[/tex] = 1-0.90
So [tex]z_{\alpha /2}=z_{0.10 /2}[/tex]
[tex]z_{\alpha /2}=z_{0.05}[/tex]
From the standard z table
[tex]z_{0.05}[/tex] = 1.645
Now putting the value in the
C.I. = [tex](\hat p \pm z_{\alpha /2}\sqrt\frac{\hat p(1-\hat p)}{n}})[/tex]
C.I. = [tex](0.45 \pm 1.645{\sqrt\frac{0.45(1-0.45)}{240}})[/tex]
Simplifying
C.I. = [tex](0.45 \pm 1.645{\sqrt\frac{0.45\times0.55}{240}})[/tex]
C.I. = [tex](0.45 \pm 1.645{\sqrt\frac{0.2475}{240}})[/tex]
C.I. = [tex](0.45 \pm 1.645\sqrt{0.001031})[/tex]
C.I. = [tex](0.45 \pm 1.645\times0.0321)[/tex]
C.I. = [tex](0.45 \pm 0.053)[/tex]
We can write it as
C.I. = {(0.45+0.053),(0.45-0.053)}
C.I. = (0.503,0.397)
Hence, a 90% confidence interval for the proportion of cell phone owners aged 18 - 24 who have an Android phone is
0.503 < p < 0.397.
To learn more about confidence interval link is here
https://brainly.com/question/24131141
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