As part of a project for his statistics class, Marcus wanted to find out the percentage of American households that still have a landline phone. He does not have any previous information or studies to examine. He would like to be [tex]99 \%[/tex] confident that his estimated population proportion is within [tex]6 \%[/tex] of the true population.

( [tex]99 \%[/tex] confidence level [tex]=z^\ \textless \ em\ \textgreater \ [/tex]-score of 2.58 )

How many households would Marcus have to survey in order to meet his requirements?

[tex]n=\hat{p}(1-\hat{p}) \cdot\left(\frac{z^\ \textless \ /em\ \textgreater \ }{E}\right)^2[/tex]

A. 99 households

B. 267 households

C. 463 households

D. 925 households



Answer :

Certainly! Let's walk through the problem step-by-step to understand how Marcus can determine the number of households he needs to survey.

1. Understanding the Given Information:
- Confidence Level: 99%
- Associated [tex]\( z \)[/tex]-score for 99% confidence: [tex]\( z^* = 2.58 \)[/tex]
- Margin of Error (E): 6% or 0.06
- Estimated Proportion [tex]\( \hat{p} \)[/tex]: Since there's no prior information, we use [tex]\( \hat{p} = 0.5 \)[/tex] (this is a standard practice to maximize the sample size).

2. Formula for Sample Size:
The formula to find the required sample size [tex]\( n \)[/tex] is:
[tex]\[ n = \hat{p}(1 - \hat{p}) \left(\frac{z^*}{E}\right)^2 \][/tex]

Here,
[tex]\[ \hat{p} = 0.5, \quad z^* = 2.58, \quad E = 0.06 \][/tex]

3. Plugging in the Values:
Let's plug these values into the formula step-by-step.
[tex]\[ n = 0.5 \times (1 - 0.5) \left(\frac{2.58}{0.06}\right)^2 \][/tex]
Simplifying further:
[tex]\[ n = 0.5 \times 0.5 \times \left(\frac{2.58}{0.06}\right)^2 \][/tex]
[tex]\[ n = 0.25 \times \left(\frac{2.58}{0.06}\right)^2 \][/tex]
[tex]\[ n = 0.25 \times \left(43\right)^2 \][/tex]
[tex]\[ n = 0.25 \times 1849 \][/tex]
[tex]\[ n = 462.25 \][/tex]

4. Rounding to the Nearest Whole Number:
Since Marcus cannot survey a fraction of a household, he must round up to the nearest whole number.
[tex]\[ n \approx 463 \][/tex]

Thus, Marcus would need to survey 463 households to meet his requirements.

From the given options, the answer is: 463 households.