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3 years ago

If u answer please I will mark you as brainliest answer....

Mathematics

1 answer:

Irina18 [472]3 years ago

6 0

I would say (C.) because the scientist only looked for the presence for both not just nickel or just lead.
Hope that helps.......if wrong I apologize.

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Suppose a 90% confidence interval for the mean salary of college graduates in a town in Mississippi is given by [$38,737, $50,46

JulsSmile [24]

Answer:

a. The point estimate was of $44,600.

b. The sample size was of 16.

Step-by-step explanation:

Confidence interval concepts:

A confidence interval has two bounds, a lower bound and an upper bound.

A confidence interval is symmetric, which means that the point estimate used is the mid point between these two bounds, that is, the mean of the two bounds.

The margin of error is the difference between the two bounds, divided by 2.

a. What is the point estimate of the mean salary for all college graduates in this town?

Mean of the bounds, so:

(38737+50463)/2 = 44600.

The point estimate was of $44,600.

b. Determine the sample size used for the analysis.

First we need to find the margin of error, so:

$M = \frac{50463-38737}{2} = 5863$

Relating the margin of error with the sample size:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1 - 0.9}{2} = 0.05$

Now, we have to find z in the Z-table as such z has a p-value of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.05 = 0.95$ , so Z = 1.64.

Now, find the margin of error M as such

$M = z\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

For this problem, we have that $\sigma = 14300, M = 5863$ . So

$M = z\frac{\sigma}{\sqrt{n}}$

$5863 = 1.645\frac{14300}{\sqrt{n}}$

$5863\sqrt{n} = 1.645*14300$

$\sqrt{n} = \frac{1.645*14300}{5863}$

$(\sqrt{n})^2 = (\frac{1.645*14300}{5863})^2$

$n = 16$

The sample size was of 16.

7 0

3 years ago

Help please and thank you

aksik [14]

Remember
$(a^b)^c=a^{bc}$
and
$\frac{x^a}{x^b}=x^{a-b}$

so

$\frac{(7^2)^5}{7^{-6}}=$
$\frac{7^{2*5}}{7^{-6}}=$
$\frac{7^{10}}{7^{-6}}=$
$7^{10-(-6)}=$
$7^{10+6}=$
$7^{16}$

the answer is D

5 0

4 years ago

The coordinates R(1, -3), S(3, -1) T(5,-7) form what type of polygon?

Reika [66]

- It's an obtuse triangle.

5 0

3 years ago

Read 2 more answers

Two poles are connected by a wire that is also connected to the ground. The first pole is 18 ft tall and the second pole is 24 f

9966 [12]

Answer:

72 feet from the shorter pole

Step-by-step explanation:

The anchor point that minimizes the total wire length is one that divides the distance between the poles in the same proportion as the pole heights. That is, the two created triangles will be similar.

The shorter pole height as a fraction of the total pole height is ...

18/(18+24) = 3/7

so the anchor distance from the shorter pole as a fraction of the total distance between poles will be the same:

d/168 = 3/7

d = 168·(3/7) = 72

The wire should be anchored 72 feet from the 18 ft pole.

_____

<em>Comment on the problem</em>

This is equivalent to asking, "where do I place a mirror on the ground so I can see the top of the other pole by looking in the mirror from the top of one pole?" Such a question is answered by reflecting one pole across the plane of the ground and drawing a straight line from its image location to the top of the other pole. Where the line intersects the plane of the ground is where the mirror (or anchor point) should be placed. The "similar triangle" description above is essentially the same approach.

Alternatively, you can write an equation for the length (L) of the wire as a function of the location of the anchor point:

L = √(18²+x²) + √(24² +(168-x)²)

and then differentiate with respect to x and find the value that makes the derivative zero. That seems much more complicated and error-prone, but it gives the same answer.

7 0

3 years ago

Complete the description of the slope of the line that joins the points

madam [21]

Step-by-step explanation:

the points are undefined

yeah I gotchuuu

5 0

3 years ago