MATHEMATICS COLLEGE

Nielsen Media Research wants to estimate the mean amount of time, in minutes, that full-time college students spend texting each weekday.Find the sample size necessary to estimate that mean with a 15 minute margin of error. Assume that a 96% confidence level is desired and that the standard deviation is estimated to be 112.2 minutes.

Answers

Answer 1

Answer:

Answer:

n=237

Step-by-step explanation:

Previous concepts

The margin of error is the range of values below and above the sample statistic in a confidence interval.

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".

Assuming the X follows a normal distribution

$X \sim N(\mu, \sigma=112.2)$

We know that the margin of error for a confidence interval is given by:

$Me=z_(\alpha/2)(\sigma)/(√(n))$ (1)

The next step would be find the value of $\z_(\alpha/2)$ , $\alpha=1-0.96=0.04$ and $\alpha/2=0.02$

Using the normal standard table, excel or a calculator we see that:

$z_(\alpha/2)=2.054$

If we solve for n from formula (1) we got:

$√(n)=(z_(\alpha/2) \sigma)/(Me)$

$n=((z_(\alpha/2) \sigma)/(Me))^2$

And we have everything to replace into the formula:

$n=((2.054(112.2))/(15))^2 =236.05$

And if we round up the answer we see that the value of n to ensure the margin of error required $\pm=15 min$ is n=237.

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True or FalseThe farther the 2-statistic is from 0, the more the null hypothesis is discredited.

Answers

Answer:

it is true

Step-by-step explanation:

A test statistic compares our observed outcome to the alternative hypothesis. If the null hypothesis is true, then the teststatistic will be close to 0. Therefore, the farther the test statistic is from 0, the more the null hypothesis is discredited.

We know that if the probability of an event happening is 100%, then the event is a certainty. Can it be concluded that if there is a 50% chance of contracting a communicable disease through contact with an infected person, there would be a 100% chance of contracting the disease if 2 contacts were made with the infected person

Answers

Answer:

The correct answer to the following question will be "No". The further explanation is given below.

Step-by-step explanation:

Probability (Keeping the disease out of 1 contact)

= $0.5$

Probability (not keeping the disease out of 1 contact)

= $1-0.5$

= $0.5$

Now,

Probability (not keeping the disease out of 2 contact)

= Keeping the disease out of 1 contact × not keeping the disease out of 1 contact

On putting the estimated values, we get

= $0.5* 0.5$

= $0.25$

So that,

Probability (Keeping the disease out of 2 contact)

= $1-0.25$

= $0.75 \ i.e., 75 \ percent$

∴ Not 100%

It takes Doug 3 days to reroof a house. If Doug's son helps, it can be done in 2 days. How long would it take Doug's son to do the job alone?

Answers

it would take his son 3 days

The weights of a certain brand of candies are normally distributed with a mean weight of 0.8547 g and a standard deviation of 0.0511 g. A sample of these candies came from a package containing 463 candies, and the package label stated that the net weight is 395.2 g. (If every package has 463 candies, the mean weight of the candies must exceed StartFraction 395.2 Over 463 EndFraction 395.2 463equals=0.8535 g for the net contents to weigh at least 395.2 g.) a. If 1 candy is randomly selected, find the probability that it weighs more than 0.8535 g. The probability is .(Round to four decimal places as needed.)

Answers

Answer:

There is a 69.15% probability that it weighs more than 0.8535 g.

Step-by-step explanation:

Problems of normally distributed samples can be solved using the z-score formula.

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

$Z = (X - \mu)/(\sigma)$

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. Subtracting 1 by the pvalue, we This p-value is the probability that the value of the measure is greater than X.

In this problem, we have that

The weights of a certain brand of candies are normally distributed with a mean weight of 0.8547 g, so $\mu = 0.8547$ .

We have a sample of 463 candies, so we have to find the standard deviation of this sample to use in the place of $\sigma$ in the Z score formula. We can do this by the following formula:

$s = (\sigma)/(√(463)) = 0.0024$

Find the probability that it weighs more than 0.8535

This is 1 subtracted by the pvalue of Z when $X = 0.8535$

$Z = (X - \mu)/(s)$

$Z = (0.8535 - 0.8547)/(0.0024)$

$Z = -0.5$

$Z = -0.5$ has a pvalue of 0.3085.

This means that there is a 1-0.3085 = 0.6915 = 69.15% probability that it weighs more than 0.8535 g.

HOME Realty claims that it can sell a detached, residential house faster than any other realty company. With the aim of examining HOME's claim, you sample 20 customers who sold a detached, residential house through HOME and record the selling times (in days) of the houses. Your data are summarized below:Selling Time Frequency
0 10 3
10 20 4
20 30 6
30 40 4
40 50 3

Find the proportion of selling times in the sample that are less than 20 days claims that it can sell a detached, residential house faster than any other realty company.

Answers

Answer:

0.35

Step-by-step explanation:

Given the data:

Selling Time___ Frequency

0 10____________3

10 20__________ 4

20 30__________ 6

30 40__________ 4

40 50__________ 3

Proportion of selling time in sample above that are less Than 20 days :

Taking the sum of the frequency :

Hence, total frequency = (3 + 4 + 6 + 4 + 3) = 20

Selling time which is less Than 20 days :

(0 - 10) = 3

(10 - 20) = 4

Total = (3 + 4) = 7

Proportion = selling time less Than 20 days / total frequency

= 7 / 20

= 0.35

1) How do you describe Ana in the selection?

Answers

Answer:

she develops a fair and healthy relationship with her classmate but also she elected the class president at their school

Step-by-step explanation:

vote me as the brainliest

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