How much money does he have

Several years ago, 38% of parents who had children in grades K-12 were satisfied with the quality of education the students r

Colt1911 [192]

Answer:

$0.428 - 1.96\sqrt{\frac{0.428(1-0.428)}{1165}}=0.3995$

$0.428 + 1.96\sqrt{\frac{0.428(1-0.428)}{1165}}=0.4564$

We are confident that the true proportion of people satisfied with the quality of education the students receive is between (0.3995, 0.4564), since the lower value for this confidence level is higher than 0.38 we have enough evidence to conclude that the parents' attitudes toward the quality of education have changed.

Step-by-step explanation:

For this case we are interesting in the parameter of the true proportion of people satisfied with the quality of education the students receive

The confidence level is given 95%, the significance level would be given by $\alpha=1-0.95=0.05$ and $\alpha/2 =0.025$ . And the critical values are:

$z_{\alpha/2}=-1.96, z_{1-\alpha/2}=1.96$

The estimated proportion of people satisfied with the quality of education the students receive is given by:

$\hat p =\frac{499}{1165}= 0.428$

The confidence interval for the proportion if interest is given by the following formula:

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

And replacing the info given we got:

$0.428 - 1.96\sqrt{\frac{0.428(1-0.428)}{1165}}=0.3995$

$0.428 + 1.96\sqrt{\frac{0.428(1-0.428)}{1165}}=0.4564$

We are confident that the true proportion of people satisfied with the quality of education the students receive is between (0.3995, 0.4564), since the lower value for this confidence level is higher than 0.38 we have enough evidence to conclude that the parents' attitudes toward the quality of education have changed.

8 0

3 years ago

The mean annual income for people in a certain city is 37 thousand dollars, with a standard deviation of 28 thousand dollars. A

Aloiza [94]

Answer:

$P( 31 < \bar X< 41)$

And we can ue the z score formula given by:

$z= \frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n}}}$

And using this formula we got for the limits:

$z = \frac{31-37}{\frac{28}{\sqrt{50}}}= -1.515$

$z = \frac{41-37}{\frac{28}{\sqrt{50}}}= 1.01$

So we want to find this probability:

$P(-1.515$

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".

Solution to the problem

Let X the random variable that represent the annual income of a population, and for this case we know the following info:

$\mu=37$ and $\sigma=28$ and we are omitting the zeros from the thousand to simplify calculations

We select a sample size of n=50>30.

The central limit theorem states that "if we have a population with mean μ and standard deviation σ and take sufficiently large random samples from the population with replacement, then the distribution of the sample means will be approximately normally distributed. This will hold true regardless of whether the source population is normal or skewed, provided the sample size is sufficiently large".

From the central limit theorem we know that the distribution for the sample mean $\bar X$ is given by:

$\bar X \sim N(\mu, \frac{\sigma}{\sqrt{n}})$

And we want to find this probability:

$P( 31 < \bar X< 41)$

And we can ue the z score formula given by:

$z= \frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n}}}$

And using this formula we got for the limits:

$z = \frac{31-37}{\frac{28}{\sqrt{50}}}= -1.515$

$z = \frac{41-37}{\frac{28}{\sqrt{50}}}= 1.01$

So we want to find this probability:

$P(-1.515$

4 0

3 years ago

What is the range of this function?<br> 543210

lutik1710 [3]

7 is the range of this function

8 0

3 years ago

Angle 1 and angle 2 form a linear pair. If the measure of angle 1 = (5x+9)º and

True [87]

- linear pairs are supplementary, meaning they add up to 180°

5x + 9 + 3x + 11 = 180

8x + 20 = 180

8x = 160

x = 20

- now plug in.

angle 1: 5(20) + 9 = 100 + 9 = 109°

angle 2: 3(20) + 11 = 60 + 11 = 71°

8 0

3 years ago

Find the volume of the rectangular prism?<br> Write your answer in simplest form.

AURORKA [14]

That’s the right answer

6 0

3 years ago