Respuesta :
Answer:
[tex] z = \frac{0.11-0.14}{0.0139} = -2.156[/tex]
And we can use the normal standard distribution table and we got:
[tex] P(Z<-2.156) =0.0155[/tex]
Step-by-step explanation:
For this case we know the following info given:
[tex] p =0.14[/tex] represent the population proportion
[tex] n = 622[/tex] represent the sample size selected
We want to find the following proportion:
[tex] P(\hat p <0.11)[/tex]
For this case we can use the normal approximation since we have the following conditions:
i) np = 622*0.14 = 87.08>10
ii) n(1-p) = 622*(1-0.14) =534.92>10
The distribution for the sample proportion would be given by:
[tex] \hat p \sim N (p ,\sqrt{\frac{p(1-p)}{n}}) [/tex]
The mean is given by:
[tex] \mu_{\hat p}= 0.14[/tex]
And the deviation:
[tex]\sigma_{\hat p}= \sqrt{\frac{0.14*(1-0.14)}{622}}= 0.0139[/tex]
We can use the z score formula given by:
[tex] z=\frac{\hat p -\mu_{\hat p}}{\sigma_{\hat p}}[/tex]
And replacing we got:
[tex] z = \frac{0.11-0.14}{0.0139} = -2.156[/tex]
And we can use the normal standard distribution table and we got:
[tex] P(Z<-2.156) =0.0155[/tex]
