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Coffee: The National Coffee Association reported that [tex]$64 \%$[/tex] of U.S. adults drink coffee daily. A random sample of 225 U.S. adults is selected. Round your answers to at least four decimal places as needed.

Part 1 of 6

(a) Find the mean [tex]$\mu_{\text{s}}$[/tex].

The mean [tex]$\mu_{\text{s}}$[/tex] is 0.64.

Part 2 of 6

(b) Find the standard deviation [tex]$\sigma_{\hat{p}}$[/tex].

The standard deviation [tex]$\sigma_{\hat{p}}$[/tex] is [tex]$\square$[/tex].

Sagot :

Let's go through the steps to find the mean and the standard deviation of the sampling distribution of the sample proportion.

### Part 1 of 6 (a)
Find the mean [tex]\(\mu_{\hat{p}}\)[/tex]:

Given data:
- Population proportion ([tex]\(p\)[/tex]) = 0.64
- Sample size ([tex]\(n\)[/tex]) = 225

The mean of the sampling distribution of the sample proportion ([tex]\(\mu_{\hat{p}}\)[/tex]) is given by the population proportion [tex]\(p\)[/tex].

[tex]\[ \mu_{\hat{p}} = p = 0.64 \][/tex]

### Part 2 of 6 (b)
Find the standard deviation [tex]\(\sigma_{\hat{p}}\)[/tex]:

The standard deviation of the sampling distribution of the sample proportion ([tex]\(\sigma_{\hat{p}}\)[/tex]) can be calculated using the formula:

[tex]\[ \sigma_{\hat{p}} = \sqrt{\frac{p(1 - p)}{n}} \][/tex]

Substitute the given values into the formula:
- [tex]\(p = 0.64\)[/tex]
- [tex]\(n = 225\)[/tex]

[tex]\[ \sigma_{\hat{p}} = \sqrt{\frac{0.64(1 - 0.64)}{225}} \][/tex]

Calculate the expression inside the square root:
[tex]\[ \sigma_{\hat{p}} = \sqrt{\frac{0.64 \times 0.36}{225}} \][/tex]

Further simplify it:

[tex]\[ \sigma_{\hat{p}} = \sqrt{\frac{0.2304}{225}} = \sqrt{0.001024} \][/tex]

Finally, take the square root to find the standard deviation:

[tex]\[ \sigma_{\hat{p}} \approx 0.032 \][/tex]

So, the standard deviation [tex]\(\sigma_{\hat{p}}\)[/tex] is approximately 0.032.