Respuesta :
Answer:
[tex]n=\frac{0.5(1-0.5)}{(\frac{0.025}{1.64})^2}=1075.84[/tex]
And rounded up we have that n=1076
Step-by-step explanation:
Information given
[tex]ME= 0.025[/tex] represent the desired margin of error
Solution
In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 90% of confidence, our significance level would be given by and . And the critical value would be given by:
[tex]t_{\alpha/2}=-1.64, t_{1-\alpha/2}=1.64[/tex]
The margin of error for the proportion interval is given by this formula:
[tex] ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}[/tex] (a)
We can assume that the best estimate for the true proportion is [tex]\hat p=0.5[/tex]. And on this case we have that [tex]ME =\pm 0.025[/tex] and we are interested in order to find the value of n, if we solve n from equation (a) we got:
[tex]n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}[/tex] (b)
And replacing into equation (b) the values from part a we got:
[tex]n=\frac{0.5(1-0.5)}{(\frac{0.025}{1.64})^2}=1075.84[/tex]
And rounded up we have that n=1076
