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Suppose that a market research firm is hired to estimate the percent of adults living in a large city who have cell phones. 500

Alborosie

Answer:

The 95% confidence interval estimate for the true proportion of adults residents of this city who have cell phones is (0.81, 0.874).

Step-by-step explanation:

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:

$n = 500, \pi = \frac{421}{500} = 0.842$

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:

$\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.842 - 1.96\sqrt{\frac{0.842*0.158}{500}} = 0.81$

The upper limit of this interval is:

$\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.842 + 1.96\sqrt{\frac{0.842*0.158}{500}} = 0.874$

The 95% confidence interval estimate for the true proportion of adults residents of this city who have cell phones is (0.81, 0.874).

6 0

3 years ago

In fraction form, what is 3/5÷1/3?<br><br>Thank you if answered

sineoko [7]

9/5 is in fraction form

6 0

3 years ago

Read 2 more answers

Kelvin can carry a basket 5 feet rachel can carry it 3 feet further than kelvin daniel can carry it half as far s rachel is it r

Ksenya-84 [330]

I think it eould be 17 feet. 5 plus 8 plus 4 is 17.

6 0

3 years ago

Find the y-intercept of f(x) = 3x^2 + 6x

Step2247 [10]

Answ3r:

81x^2

Step-by-step explanation

I think

4 0

2 years ago

Read 2 more answers

Three potential employees took an aptitude test. Each person took a different version of the test. The scores are reported below

BARSIC [14]

Answer:

Due to the higher Z-score, Demetria should be offered the job.

Step-by-step explanation:

Z-score:

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

In this question:

Whichever applicant had grade with the highest z-score should be offered the job.

Demetria got a score of 85.1; this version has a mean of 61.1 and a standard deviation of 12.

For Demetria, we have $X = 85.1, \mu = 61.1, \sigma = 12$ . So