Respuesta :
Answer:
a)Randomization condition: Satisfied, as the subjects were randomly selected.
10% condition: Satisfied, as the sample size is less than 10% of the population (U.S. adults).
Sample size condition: Satisfied, as the product between the smaller proportion and the sample size is bigger than 10.
b) The 90% confidence interval for the population proportion is (0.68, 0.70).
Step-by-step explanation:
a) Evaluating the necessary conditions:
Randomization condition: Satisfied, as the subjects were randomly selected.
10% condition: Satisfied, as the sample size is less than 10% of the population (U.S. adults).
Sample size condition: Satisfied, as the product between the smaller proportion and the sample size is bigger than 10.
[tex]n(1-p)=4,726\cdot (1-0.69)=4,726\cdot 0.31=1,465>10[/tex]
b) We have to calculate a 90% confidence interval for the proportion.
The sample proportion is p=0.69.
The standard error of the proportion is:
[tex]\sigma_p=\sqrt{\dfrac{p(1-p)}{n}}=\sqrt{\dfrac{0.69*0.31}{4726}}\\\\\\ \sigma_p=\sqrt{0.000045}=0.007[/tex]
The critical z-value for a 90% confidence interval is z=1.645.
The margin of error (MOE) can be calculated as:
[tex]MOE=z\cdot \sigma_p=1.645 \cdot 0.007=0.01[/tex]
Then, the lower and upper bounds of the confidence interval are:
[tex]LL=p-z \cdot \sigma_p = 0.69-0.01=0.68\\\\UL=p+z \cdot \sigma_p = 0.69+0.011=0.70[/tex]
The 90% confidence interval for the population proportion is (0.68, 0.70).
