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3 years ago

The sum of twice a number and five is 13. Find the number.

Mathematics

2 answers:

Arlecino [84]3 years ago

8 0

Answer:

the number is 4

Step-by-step explanation:

let the number be ''x''

than twice the number will be 2x

now,

2x + 5 = 13

2x = 13 - 5

2x = 8

x = 8/2

x= 4

Eduardwww [97]3 years ago

6 0

let the number be x

so by the question , 2x+5=13

solving this we get ,

2x=13-5

2x=8

so x=4

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In a random sample of 150 customers of a high-speed Internetprovider, 63 said that their service had been interrupted one ormore

erastovalidia [21]

Answer:

a) The 95% confidence interval would be given by (0.341;0.499)

b) The 99% confidence interval would be given by (0.316;0.524)

c) n=335

d)n=649

Step-by-step explanation:

1) Notation and definitions

$X_{IS}=63$ number of high speed internet users that had been interrupted one or more times in the past month.

$n=150$ random sample taken

$\hat p_{IS}=\frac{63}{150}=0.42$ estimated proportion of high speed internet users that had been interrupted one or more times in the past month.

$p_{IS}$ true population proportion of high speed internet users that had been interrupted one or more times in the past month.

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".

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})$

1) Part a

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by $\alpha=1-0.95=0.05$ and $\alpha/2 =0.025$ . And the critical value would be given by:

$t_{\alpha/2}=-1.96, t_{1-\alpha/2}=1.96$

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

$\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$

If we replace the values obtained we got:

$0.42 - 1.96\sqrt{\frac{0.42(1-0.42)}{150}}=0.341$

$0.42 + 1.96\sqrt{\frac{0.42(1-0.42)}{150}}=0.499$

The 95% confidence interval would be given by (0.341;0.499)

2) Part b

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 99% of confidence, our significance level would be given by $\alpha=1-0.99=0.01$ and $\alpha/2 =0.005$ . And the critical value would be given by:

$t_{\alpha/2}=-2.58, t_{1-\alpha/2}=2.58$

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

$\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$

If we replace the values obtained we got:

$0.42 - 2.58\sqrt{\frac{0.42(1-0.42)}{150}}=0.316$

$0.42 + 2.58\sqrt{\frac{0.42(1-0.42)}{150}}=0.524$

The 99% confidence interval would be given by (0.316;0.524)

3) Part c

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.05$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

And replacing into equation (b) the values from part a we got:

$n=\frac{0.42(1-0.42)}{(\frac{0.05}{1.96})^2}=374.32$

And rounded up we have that n=335

4) Part d

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.05$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

And replacing into equation (b) the values from part a we got:

$n=\frac{0.42(1-0.42)}{(\frac{0.05}{2.58})^2}=648.599$

And rounded up we have that n=649

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3 years ago

Find the domain and range of the function

SVEN [57.7K]

Answer:

domain: (-∞ , ∞)

range: (-∞, 2]

Step-by-step explanation:

the domain is the set of values of what the x value can be. This function is parabolic and upside down, it can have a range of x values from - infinity to positive infinity. The function is most likely y=-x^2 +2

range is the output (y values) the function can possibly have. the max is 2 and includes 2 so we use bracket for that. The smallest y value can reach towards negative infinity.

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3 years ago

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Find f(x) and g(x) so that the function can be described as y = f(g(x)). <br><br> y = 7/sqrt 8x +10

Blizzard [7]

Assuming you meant

$y = \frac{7}{ \sqrt{8x+10} }$

Then you can compose the function g(x)

$g(x)= \sqrt{8x+10}$

With the function

$f(x)= \frac{7}{x}$

Because f (g(x) ) means that you first find (calculte) $\sqrt{8x+10}$ and second you divide 7 by g(x) to obtain 7 / [√(8x+10) ].

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3 years ago

Need help asap!!! just number 5 i’ll give you brainiest answer!

liberstina [14]

Answer:

Step-by-step explanation:

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3 years ago

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jarptica [38.1K]

For
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3 years ago