<img src="https://tex.z-dn.net/?f=x%3D-2%5C%5Cx%2B3y%3D4" id="TexFormula1" title="x=-2\\x+3y=4" alt="x=-2\\x+3y=4" align="absmid

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 $\alpha=1-0.90=0.1$ and $\alpha/2 =0.05$ . And the critical value would be given by:

$z_{\alpha/2}=-1.64, z_{1-\alpha/2}=1.64$

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.04$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

We assume that a prior estimation for p would be $\hat p =0.5$ since we don't have any other info provided. And replacing into equation (b) the values from part a we got:

$n=\frac{0.5(1-0.5)}{(\frac{0.04}{1.64})^2}=420.25$

And rounded up we have that n=421

5 0

3 years ago

Select the correct answer<br> What is the sum of -6 4/5 and 6 4/5?

forsale [732]

Answer: 0

Step-by-step explanation: -6.80 + 6.80

Negative numbers act as subtracting

5 0

3 years ago

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