Amira is painting a rectangular banner 2 1/4 yards wide on a wall in the cafeteria.

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

Find the values ofx and y for the triange.<br> x<br> 60°<br> 30°<br> у

egoroff_w [7]

Answer:

x = 42, y = 36.37

Step-by-step explanation:

6 0

3 years ago

Read 2 more answers

For the graph x = -3 find the slope of a line that is parallel to it.

shutvik [7]

The ilne paralell to x=something is x=something else (both are constants)

slope=rise/run

x=-3
it rises infiniley and runs 0 (goes left to right 0)
slope=infinity/0=undefined

the slope is undefined
paralell lines have same slope
so the slope of a paralell line is also undefined

3 0

3 years ago

Read 2 more answers

The Thomas family bought 5 subs and 4 drinks. They spent 49.50 write and equation that models this situation define x and y vari

OlgaM077 [116]

Answer:

5x+4y=49.50, where:

x is the price per sub

y is the price per drink

Step-by-step explanation:

From the information provided, you can say that the result of adding up the price per sub for the quantity plus the price per drink for the quantity is equal to 49.50 that is the total amount spent, which can be expressed as:

5x+4y=49.50, where:

x is the price per sub

y is the price per drink

5 0

3 years ago

Peaches are being sold for $2 dollars per pound if x represents the number of pounds of peaches bought and y represents the tota

Alex787 [66]

I'm guessing you want an equation.

In that case, the equation would be $2x =y

8 0

3 years ago