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2 years ago

8

What causes the phases of the moon? A) The amount of sunlight reflected onto the moon from the sun B) The Moon Earth and Sun are

lined up in the same place C) It is closer to the Earth at times and further from the earth at other times D) The effect of gravity

1 answer:

bagirrra123 [75]2 years ago

8 0

A: because the suns light on the moon is what we see

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A random sample of size n1= 25, taken from a normal population with a standard deviation σ1= 5, has a mean X1= 80. A second rand

sesenic [268]

Answer:

The 94% confidence interval would be given by $2.898 \leq \mu_1 -\mu_2 \leq 7.102$

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

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".

$\bar X_1 =80$ represent the sample mean 1

$\bar X_2 =75$ represent the sample mean 2

n1=25 represent the sample 1 size

n2=36 represent the sample 2 size

$\sigma_1 =5$ sample standard deviation for sample 1

$\sigma_2 =3$ sample standard deviation for sample 2

$\mu_1 -\mu_2$ parameter of interest.

The confidence interval for the difference of means is given by the following formula:

$(\bar X_1 -\bar X_2) \pm z_{\alpha/2}\sqrt{\frac{\sigma^2_1}{n_1}+\frac{\sigma^2_2}{n_2}}$ (1)

The point of estimate for $\mu_1 -\mu_2$ is just given by:

$\bar X_1 -\bar X_2 =80-75=5$

Since the Confidence is 0.94 or 94%, the value of $\alpha=0.06$ and $\alpha/2 =0.03$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.03,0,1)".And we see that $z_{\alpha/2}=1.88$

The standard error is given by the following formula:

$SE=\sqrt{\frac{\sigma^2_1}{n_1}+\frac{\sigma^2_2}{n_2}}$

And replacing we have:

$SE=\sqrt{\frac{5^2}{25}+\frac{3^2}{36}}=1.118$

Confidence interval

Now we have everything in order to replace into formula (1):

$5-1.88\sqrt{\frac{5^2}{25}+\frac{3^2}{36}}=2.898$

$5+1.8\sqrt{\frac{6^2}{36}+\frac{7^}{49}}=7.102$

So on this case the 94% confidence interval would be given by $2.898 \leq \mu_1 -\mu_2 \leq 7.102$

7 0

2 years ago

What are three collinear points in the figure below?

algol [13]

Answer:

B. W,V,Z

Step-by-step explanation:

Collinear points are two more points in the same plane that lie in a straight line.

From the diagram, Z is the intersection of the two diagonals of quadrilateral VXWY.

The points V, Z and W lie along the same diagonal, hence they are collinear.

The point y, Z, and X also lie along the same diagonal, these are also collinear.

The correct choice is B

7 0

2 years ago

I need help please and thank you

Andreas93 [3]

Answer:

Well doesn't it say that the brand has seven sizes, so doesn't that mean that there are 7 available jeans.

Step-by-step explanation:

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2 years ago

Find the volume of the triangular prism.<br> NEED ASAP PLS

Alexus [3.1K]

Answer:

32 inches cubed

Step-by-step explanation:

Multiply the length by the width: 4*4=16

Multiply by 12: 16*1/2=8

Multiply by height: 4*8=32

Hope this helped!

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2 years ago

Read 2 more answers

kifflom [539]

Answer:

about 28

Step-by-step explanation:

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3 years ago