2x=-y in standard form

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

Writing algebraic expressions for: A number decreased by 5 is 12

snow_lady [41]

Answer:

x-5=12

hope this helps

6 0

3 years ago

James is kayaking. He can row 3 mph in still water. If he can travel 6 miles downstream in the same amount of time that he can t

nekit [7.7K]

Answer: the speed of the current is 0.6 mph

Step-by-step explanation:

Let x represent the speed of the current.

James is kayaking. He can row 3 mph in still water. If he can travel 6 miles downstream. Assuming he went with the current, it means that his total speed while travelling downstream is (3 + x)

Time = distance/speed

Time taken to travel downstream is

6/(3 + x)

In the same amount of time, he can travel 4 miles upstream. Assuming he went against the current, it means that his total speed while travelling downstream is (3 - x). Time taken to travel upstream is

4/(3 - x)

Since the time is the same, then

6/(3 + x) = 4/(3 - x)

Cross multiplying, it becomes

6(3 - x) = 4(3 + x)

18 - 6x = 12 + 4x

4x + 6x = 18 - 12

10x = 6

x = 6/10

x = 0.6 mph

4 0

3 years ago

If p = .8 and n = 50, then we can conclude that the sampling distribution of pˆ is approximately a normal distribution

FrozenT [24]

Answer:

Yes we can conclude.

Step-by-step explanation:

The sampling distribution of $\hat{p}$ can be approximated as a Normal Distribution only if:

np and nq are both equal to or greater than 10. i.e.

np ≥ 10
nq ≥ 10

Both of these conditions must be met in order to approximate the sampling distribution of $\hat{p}$ as Normal Distribution.

From the given data:

n = 50

p = 0.80

q = 1 - p = 1 - 0.80 = 0.20

np = 50(0.80) = 40

nq = 50(0.20) = 10

This means the conditions that np and nq must be equal to or greater than 10 is being satisfied. So, we can conclude that the sampling distribution of pˆ is approximately a normal distribution

6 0

3 years ago

Which statement is true about the equations –3x + 4y = 12 and 1/4x –1/3 y = 1?The system of the equations has exactly one soluti

iren [92.7K]

Answer:

The system of the equations has no solution; the two lines are parallel.

Step-by-step explanation:

The equations have the same slope. In standard form, this can be seen as the same coefficients for x and y. We will multiply the second equation by -12 to reveal this.

$\frac{1}{4} x-\frac{1}{3}y=1 \\-12(\frac{1}{4} x-\frac{1}{3}y=1)\\\frac{-12}{4} x-\frac{-12}{3}y=-12\\-3x+4y=-12$

This means the equations are parallel and will never cross. There is no solution.

4 0

3 years ago