In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

For this problem, we have that:

$n = 865, \pi = \frac{408}{865} = 0.4717$

95% confidence level

So $\alpha = 0.05$ , z is the value of Z that has a pvalue of $1 - \frac{0.05}{2} = 0.975$ , so $Z = 1.96$ .

The lower limit of this interval is:

$\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.4717 - 1.96\sqrt{\frac{0.4717*0.5283}{865}} = 0.4384$

The upper limit of this interval is:

$\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.4717 + 1.96\sqrt{\frac{0.4717*0.5283}{865}} = 0.5050$

The 95% confidence interval for the true proportion of all voters in the state who favor approval is (0.4384, 0.5050).

6 0

2 years ago

4w+5z=30 solve for w

zepelin [54]

Answer:

$w=\frac{30-5z}{4}$

Step-by-step explanation:

$4w+5z=30\\\\4w+5z-5z=30-5z\\\\4w=30-5z\\\\\frac{4w=30-5z}{4}\\\\\boxed{w=\frac{30-5z}{4}}$

Hope this helps.

3 0

3 years ago