<img src="https://tex.z-dn.net/?f=%20%5Cfrac%7B3%7D%7B4%7D%20%20%5Ctimes%208" id="TexFormula1" title=" \frac{3}{4} \times 8" al

Suppose that a researcher is designing a survey to estimate the proportion of adults in your state who oppose a proposed law tha

irinina [24]

Answer:

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

So without prior estimation for the population proportion, using a confidence level of 95% if we want a margin of error about 2% we need al least a sample size of 2401.

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".

The population proportion have the following distribution

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

Solution to the problem

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)

If solve n from equation (a) we got:

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

The margin of error desired for this case is $ME= \pm 0.02$ equivalent to 2% points

For this case we need to assume a confidence level, let's assume 95%. And since we don't have prior estimation for the population proportion of interest the best value to do an approximation is $\hat p =0.5$

In order to find the critical value we need to take in count that we are finding the margin of error 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:

$z_{\alpha/2}=\pm 1.96$

Now we have all the values needed and if we replace into equation (b) we got:

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

So without prior estimation for the population proportion, using a confidence level of 95% if we want a margin of error about 2% we need al least a sample size of 2401.

5 0

3 years ago

A cross-country team had a total of 10 practices last week, with each practice being in the morning or the afternoon. During eac

GalinKa [24]

x= morning

y = afternoon

x + y = 10

x=10-y

5x + 6y =57

5(10-y) +6y =57

50-5y +6y =57

y=7

x=10-7 =3

check 3*5 = 15, 7*6 = 42, 42 + 15 = 57

3 morning practices

3 0

3 years ago

An open box is to be made out of a 12-inch by 20-inch piece of cardboard by cutting out squares of equal size from the four corn

Natali5045456 [20]

Answer:

Length = 15.14, width = 7.14 and height = 2.43 inches.

( correct to the nearest hundredth).

Step-by-step explanation:

Let the lengths of the squares cut out be x inches.

Then the width of the box will be 12 - 2x and the length will be

20 - 2x inches.

The height of the box is x inches.

Volume V = x(20-2x)(12-2x)

To find the value of x when V is a maximum we find the derivative and equate it to zero.

V = x( 240 - 64x + 4x^2)

V = 4x^3 - 64x^2 + 240x

dV/dx = 12x^2 - 128x + 240 = 0

4(3x^2 - 32x + 60) = 0

This won't factor so we use the formula:

x = [-(-32) +/- √((-32)^2 - 4*3*60)] / 6

= 8.24, 2.43.

So one of these gives a maximum Volume.

The second derivative

d^2V/dx^2 = 24x - 128

When x = 8.24, this = 69.6 (positive) so this gives a minimum.

x = 2.43 gives a negative value ( -49.7) so this is the maximum

So the dimensions are:-

length = 20 - 2(2.43) = 15.14

width = 12 - 2(2.43) = 7.14

height = 2.43.

7 0

2 years ago

The area of a rectanglular sandbox is (5x + 40) feet. Factor 5x + 40 to find possible dimensions of the sandbox

kotegsom [21]

5x+40 factors to 5(x+8). Notice how distributing the 5 back through to each term in the parenthesis gives
5 times x = 5x
5 times 8 = 40
So 5*(x+8) = 5*x+5*8 = 5x+40

Therefore, the factors are 5 and (x+8).
The dimensions of the sandbox are 5 feet by (x+8) feet.

We don't know the numeric value of (x+8) since we don't know the value of x, so we leave it as is.

6 0

3 years ago

What is the reminder? Help

Vanyuwa [196]

Answer:

6

Step-by-step explanations:

The remainder is what is left over after dividing whatever from d. So if you add one to d, then the remainder would increase from 5 to 6.

Hope this helps.

4 0

3 years ago