Respuesta :
Answer:
The 95% confidence interval estimate for the true proportion of adults residents of this city who have cell phones is (0.81, 0.874).
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of [tex]\pi[/tex], and a confidence level of [tex]1-\alpha[/tex], we have the following confidence interval of proportions.
[tex]\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]
In which
z is the zscore that has a pvalue of [tex]1 - \frac{\alpha}{2}[/tex].
For this problem, we have that:
[tex]n = 500, \pi = \frac{421}{500} = 0.842[/tex]
95% confidence level
So [tex]\alpha = 0.05[/tex], z is the value of Z that has a pvalue of [tex]1 - \frac{0.05}{2} = 0.975[/tex], so [tex]Z = 1.96[/tex].
The lower limit of this interval is:
[tex]\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.842 - 1.96\sqrt{\frac{0.842*0.158}{500}} = 0.81[/tex]
The upper limit of this interval is:
[tex]\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.842 + 1.96\sqrt{\frac{0.842*0.158}{500}} = 0.874[/tex]
The 95% confidence interval estimate for the true proportion of adults residents of this city who have cell phones is (0.81, 0.874).
The 95% confidence interval is (0.81,0.874) and this can be determined by using the confidence interval formula and using the given data.
Given :
- 500 randomly selected adult residents in this city are surveyed to determine whether they have cell phones.
- Of the 500 people surveyed, 421 responded yes – they own cell phones.
- 95% confidence level.
The formula for the confidence interval is given by:
[tex]\rm CI = p\pm z\sqrt{\dfrac{p(1-p)}{n}}[/tex] --- (1)
where the value of p is given by:
[tex]\rm p =\dfrac{421}{500}=0.842[/tex]
Now, the value of z for 95% confidence interval is given by:
[tex]\rm p-value = 1-\dfrac{0.05}{2}=0.975[/tex]
So, the z value regarding the p-value 0.975 is 1.96.
Now, substitute the value of z, p, and n in the expression (1).
[tex]\rm CI = 0.842\pm 1.96\sqrt{\dfrac{0.842(1-0.842)}{500}}[/tex]
The upper limit is 0.81 and the lower limit is 0.874 and this can be determined by simplifying the above expression.
So, the 95% confidence interval is (0.81,0.874).
For more information, refer to the link given below:
https://brainly.com/question/23044118