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3 years ago

Which expression is equivalent to ?

Mathematics

2 answers:

Aloiza [94]3 years ago

8 0

Answer: 2x^10y^12

Step-by-step explanation:

the second one.

60/30 = 2

x^20 - x^10 = x^10

y^24 - y^12 = y^12

ivann1987 [24]3 years ago

6 0

Answer:

2x Y,

Step-by-step explanation:

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Simplify all the ratios. Show your work!

Dmitrij [34]

I can help u but just give me 5 mins or 2 to help u :) ill get back to u right away

4 0

3 years ago

Researchers are interested if a school breakfast program leads to taller children. Assume that the population of all 5 year-old

DedPeter [7]

Answer:

$39-1.96\frac{1}{\sqrt{25}}=38.608$

$39+1.96\frac{1}{\sqrt{25}}=39.392$

So on this case the 95% confidence interval would be given by (38.608;39.392)

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".

$\bar X=39$ represent the sample mean for the sample

$\mu$ population mean (variable of interest)

$\sigma=1$ represent the population standard deviation

n=25 represent the sample size

Solution to the problem

The confidence interval for the mean is given by the following formula:

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

The margin of error is given by:

$ME= z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$

Since the Confidence is 0.95 or 95%, the value of $\alpha=0.05$ and $\alpha/2 =0.025$ , and we can use excel, a calculator or a tabel to find the critical value. The excel command would be: "=-NORM.INV(0.025,0,1)".And we see that $z_{\alpha/2}=1.96$

And replacing we got:

$ME= 1.96 *\frac{1}{\sqrt{25}}= 0.392$

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

$39-1.96\frac{1}{\sqrt{25}}=38.608$

$39+1.96\frac{1}{\sqrt{25}}=39.392$

So on this case the 95% confidence interval would be given by (38.608;39.392)

7 0

3 years ago

Let x be a random variable with pmf pk = c/k2 for k = 1, 2, …a. estimate the value of c numerically. note that the series conver

kaheart [24]

$f_X(x)=\begin{cases}\dfrac c{k^2}&\text{for }k\in\{1,2,\ldots\}\\0&\text{otherwise}\end{cases}$

Because this is a valid PMF, you must have

$\displaystyle\sum_{k\ge1}f_X(x)=\sum_{k\ge1}\frac c{k^2}=1$

Recall that

$\displaystyle\sum_{k\ge1}\frac1{k^2}=\dfrac{\pi^2}6$

so the above sum is

$\displaystyle\sum_{k\ge1}\frac c{k^2}=\frac{c\pi^2}6=1$

which means that you must have

$c=\dfrac6{\pi^2}\approx0.6079$