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3 years ago

7

The difference of the sample means of two populations is 34.6, and the standard deviation of the difference of the sample means

is 11.9. The 95% confidence interval lies between A) -11.9 B) -23.8 C) -35.7 D) -45.4 and A) 11.9 B) 23.8 C) 35.7 D) 45.4

1 answer:

mojhsa [17]3 years ago

8 0

Answer

23.8,23.8

Step-by-step explanation:

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Whats the diffenition of constant

REY [17]

Answer:

definition of constant

Step-by-step explanation:

the definition of constant is occurring countinuosly over a period of time

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3 years ago

What is 3 = 5x - 12?

zepelin [54]

Answer:

x = 3

Step-by-step explanation:

3=5x-12

Rearrange the Equation.

5x - 12 = 3

Add 12 to both sides.

5x - 12 + 12 = 3 + 12

Simplify

5x = 15

Divide both sides by 5

5x/5 = 15/5

x = 3

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4 years ago

The ratio of men to women in a movie theater is 3:5. As two more men and one more woman walk in, the ratio of men to women becom

34kurt

Answer:

C. 20

Step-by-step explanation:

Let's say M is the original number of men and W is the original number of women.

M / W = 3 / 5

(M+2) / (W+1) = 2 / 3

Let's cross multiply both equations:

5M = 3W

3(M+2) = 2(W+1)

Let's simplify the second equation:

3M + 6 = 2W + 2

3M + 4 = 2W

From the first equation:

M = 3/5 W

Substitute:

3 (3/5 W) + 4 = 2W

9/5 W + 4 = 2W

4 = 1/5 W

W = 20

There were originally 20 women.

Let's check our answer. That would mean that M = 3/5 W = 12.

After 2 men walk in and 1 woman, W = 21 and M = 14, so 14/21 = 2/3. Looks like the answer is correct!

Answer C.

7 0

4 years ago

The mean number of words per minute (WPM) read by sixth graders is 8888 with a standard deviation of 1414 WPM. If 137137 sixth g

Bingel [31]

Noticing that there is a pattern of repetition in the question (the numbers are repeated twice), we are assuming that the mean number of words per minute is 88, the standard deviation is of 14 WPM, as well as the number of sixth graders is 137, and that there is a need to estimate the probability that the sample mean would be greater than 89.87.

Answer:

"The probability that the sample mean would be greater than 89.87 WPM" is about $\\ P(z>1.56) = 0.0594$ .

Step-by-step explanation:

This is a problem of the <em>distribution of sample means</em>. Roughly speaking, we have the probability distribution of samples obtained from the same population. Each sample mean is an estimation of the population mean, and we know that this distribution behaves <em>normally</em> for samples sizes equal or greater than 30 $\\ n \geq 30$ . Mathematically

$\\ \overline{X} \sim N(\mu, \frac{\sigma}{\sqrt{n}})$ [1]

In words, the latter distribution has a mean that equals the population mean, and a standard deviation that also equals the population standard deviation divided by the square root of the sample size.

Moreover, we know that the variable Z follows a <em>normal standard distribution</em>, i.e., a normal distribution that has a population mean $\\ \mu = 0$ and a population standard deviation $\\ \sigma = 1$ .

$\\ Z = \frac{\overline{X} - \mu}{\frac{\sigma}{\sqrt{n}}}$ [2]

From the question, we know that

The population mean is $\\ \mu = 88$ WPM
The population standard deviation is $\\ \sigma = 14$ WPM

We also know the size of the sample for this case: $\\ n = 137$ sixth graders.

We need to estimate the probability that a sample mean being greater than $\\ \overline{X} = 89.87$ WPM in the <em>distribution of sample means</em>. We can use the formula [2] to find this question.

The probability that the sample mean would be greater than 89.87 WPM

$\\ Z = \frac{\overline{X} - \mu}{\frac{\sigma}{\sqrt{n}}}$

$\\ Z = \frac{89.87 - 88}{\frac{14}{\sqrt{137}}}$

$\\ Z = \frac{1.87}{\frac{14}{\sqrt{137}}}$

$\\ Z = 1.5634 \approx 1.56$

This is a <em>standardized value </em> and it tells us that the sample with mean 89.87 is 1.56<em> standard deviations</em> <em>above</em> the mean of the sampling distribution.

We can consult the probability of P(z<1.56) in any <em>cumulative</em> <em>standard normal table</em> available in Statistics books or on the Internet. Of course, this probability is the same that $\\ P(\overline{X} < 89.87)$ . Then

$\\ P(z$

However, we are looking for P(z>1.56), which is the <em>complement probability</em> of the previous probability. Therefore

$\\ P(z>1.56) = 1 - P(z$

$\\ P(z>1.56) = P(\overline{X}>89.87) = 0.0594$

Thus, "The probability that the sample mean would be greater than 89.87 WPM" is about $\\ P(z>1.56) = 0.0594$ .

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3 years ago

Need help please !!!!!<br><br> Will mark as brainliest!!!!<br><br> (Don’t mind my answers)

Alika [10]

Answer:

Can you give me the choices for each of these, I'm not sure how they might phrase it.

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3 years ago