In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence interval $1-\alpha$ , 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 $1 - \frac{\alpha}{2}$ .

And the margin of error is:

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

95% confidence interval

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

In this problem, we have that:

$M = 0.04, p = 0.35$

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

$0.04 = 1.96\sqrt{\frac{0.35*0.65}{n}}$

$0.04\sqrt{n} = 0.93486$

$\sqrt{n} = 23.37$

$n = 546.2275$

At least 547 records need to be studied.

6 0

3 years ago

Find the equation of the axis of symmetry for the parabola y = x2 + 2x − 9

Artemon [7]

Answer:

the answer is x=-1

Step-by-step explanation:

5 0

3 years ago

Read 2 more answers

Compute 2/3 x 1/3 + 1/3 (3 + 1/3) and express your answer as a mixed number. (Note that 3 1/3 should be read as a mixed number).

Dominik [7]

Answer:

1 1/3

Step-by-step explanation:

First, distribute the parenthesis.

Second, multiply the fractions.

Third, add the 2 values together to get your answer in improper form.

Lastly, turn the improper fraction into mixed form.

4 0

3 years ago