I don’t know how to do it please help me

Mathematics

1 answer:

viktelen [127]2 years ago

6 0

Answer:

its 18ft

Step-by-step explanation:

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AlladinOne [14]

Using the z-distribution, a sample size of 180 is needed for the estimate.

<h3>What is a z-distribution confidence interval?</h3>

The confidence interval is:

$\overline{x} \pm z\frac{\sigma}{\sqrt{n}}$

The margin of error is given by:

$M = z\frac{\sigma}{\sqrt{n}}$

In which:

$\overline{x}$ is the sample mean.

z is the critical value.

n is the sample size.

$\sigma$ is the standard deviation for the population.

In this problem, we have a 98% confidence level, hence $\alpha = 0.98$ , z is the value of Z that has a p-value of $\frac{1+0.98}{2} = 0.99$ , so the critical value is z = 2.327.

The population standard deviation is of $\sigma = 23$ , and to find the sample size, we have to solve for n when M = 4.

Hence:

$M = z\frac{\sigma}{\sqrt{n}}$

$4 = 2.327\frac{23}{\sqrt{n}}$

$4\sqrt{n} = 2.327 \times 23$

$\sqrt{n} = \frac{2.327 \times 23}{4}$

$(\sqrt{n}) = \left(\frac{2.327 \times 23}{4}\right)^2$

n = 179.03.

Rounding up, as a sample size of 179 would result in an error slightly above 4, a sample of 180 is needed.

More can be learned about the z-distribution at brainly.com/question/25890103

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8 0

2 years ago

PLS HELP ME! FOR 50 POINTS!!! I will give brainliest!

lbvjy [14]

Answer:

$\frac{x - 3}{x + 4} \div \frac{x ^{2} - 1 }{ x} \\ = \frac{x - 3}{x + 4} \times \frac{x}{ {x}^{2} - 1} \\ =\frac{x(x - 3)}{(x + 4)( {x}^{2} - 1) } \\= \frac{x(x - 3)}{(x + 4)(x + 1)(x - 1)}$