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3 years ago

I'm about to give 100 pts who wants em?

Mathematics

2 answers:

S_A_V [24]3 years ago

7 0

Answer:

me lollll

Step-by-step explanation:

ivann1987 [24]3 years ago

6 0

Answer:

thx for the points

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Nitrates are groundwater contaminants derived from fertilizer, septic tank seepage and other sewage. Nitrate poisoning is partic

o-na [289]

Answer:

a) $n=\frac{0.5(1-0.5)}{(\frac{0.02}{1.96})^2}=2401$

And rounded up we have that n=2401

b) $n=\frac{0.07(1-0.07)}{(\frac{0.02}{1.96})^2}=625.22$

And rounded up we have that n=626

And we see that if we have previous info about p the sample size varies a lot.

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".

Solution to the problem

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:

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

Part a

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 $ME =\pm 0.02$ 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)

Since we don't have prior information about the population proportion we can use ase estimator $\hat p =0.5$ . And replacing into equation (b) the values from part a we got:

$n=\frac{0.5(1-0.5)}{(\frac{0.02}{1.96})^2}=2401$

And rounded up we have that n=2401

Part b

For thi case the estimator for p is $\hat p =0.07$

$n=\frac{0.07(1-0.07)}{(\frac{0.02}{1.96})^2}=625.22$

And rounded up we have that n=626

And we see that if we have previous info about p the sample size varies a lot.

4 0

3 years ago

The difference between the MDC and the LDC's

Contact [7]

Answer: MDCs have advanced socially and economically, whereas LDCs are in the early stages of development.

8 0

2 years ago

I need help with question 30..

Aloiza [94]

Let's say 1000 dollars was spent on all of these. That would mean 170 dollars and 240 were spent on food and entertainment respectivly. If we want to see how much of the total cost was spent on these things, we would have to add them and divide them by 1000, so:

$\frac{170+240}{1000}=\frac{410}{1000}=frac{41}{100}$

6 0

3 years ago

part 3. Find the coordinates of the vertices of the triangle after a reflection across the y-axis and then across the line y= 2.

garik1379 [7]

Answer:

c. S'(3, 1), T'(1, -1), U'(0, 1)

Step-by-step explanation:

Reflection across the y-axis negates the x-coordinate, so is equivalent to the transformation ...

(x, y) ⇒ (-x, y)

Reflection across the horizontal line y=c is equivalent to the transformation ...

(x, y) ⇒ (x, 2c-y)

So, the combined reflections are equivalent to the transformation ...

(x, y) ⇒ (-x, 4 -y)

Then we have ...

S(-3, 3) ⇒ S'(-(-3), 4-3) = S'(3, 1)

T(-1, 5) ⇒ T'(-(-1), 4-5) = T'(1, -1)

U(0, 3) ⇒ U'(-(0), 4-3) = U'(0, 1) . . . . matches choice C

7 0

3 years ago

Sara had some buns she sold 5/9 of them, if she has 128 buns left. How many bums did she have at first?

mina [271]

Step-by-step explanation:

Maybe she had

128 + 9 = 137 buns

7 0

3 years ago

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