According to a poll, 55 % of Americans do not know that GOP stands for Grand Old Party (Time, October 17, 2011). Assume that this percentage is true for the current population of Americans. Let p ^ be the proportion in a random sample of 953 Americans who do not know that GOP stands for Grand Old Party. Find the mean and standard deviation of the sampling distribution of p ^ and describe its shape.

Answer :

Answer:

[tex]\hat p  \sim N (p , \sqrt{\frac{p(1-p)}{n}}) [/tex]

The mean is given by:

[tex] \mu_{\hat p} = 0.55[/tex]

And the deviation:

[tex] \sigma_{\hat p} =\sqrt{\frac{0.55*(1-0.55)}{953}}= 0.0161[/tex]

Step-by-step explanation:

For this case we assume that the true population proportion of Americans do not know that GOP stands for Grand Old Party is 0.55 and we select a random sample of n = 953 americans

For this case we assume that we satisfy the conditions to use the normal approximation for [tex]\hat p[/tex]

1) np >10 , n(1-p)>10

2) Independence

3) Random sample

4) The sample size is less than 10% of the population size

We assume that all the conditions are satisfied and the distribution for [tex]\hat p[/tex] would be:

[tex]\hat p  \sim N (p , \sqrt{\frac{p(1-p)}{n}}) [/tex]

The mean is given by:

[tex] \mu_{\hat p} = 0.55[/tex]

And the deviation:

[tex] \sigma_{\hat p} =\sqrt{\frac{0.55*(1-0.55)}{953}}= 0.0161[/tex]

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