Answer these 3 questions ASAP pls..

Roberta needs 12 zippers to make 3 of the same backpacks. If Roberta has 48 zippers, how many of those same backpacks can she ma

yaroslaw [1]

First, you need to find out how many zippers are used to make one bookbag. To do that, you divide the zippers used to make the 3 backpacks.

12 / 3 = 4

So, 4 zippers are used per bookbag. Then, you divide the number of available zippers by four to find out how many bags she can make.

48 / 4 = 12

Roberta can make 12 bookbags.

5 0

3 years ago

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

Pls help show work please

Aloiza [94]

Each bracelet is $5, this can be represented as 5b. (Where b is number of bracelets)

Each necklace is $8, this can be represented as 8n. (Where n is number of necklaces)

We know that the total money raised needs to be at least $100, but it can also be more than that.

So we know that 8n+5b will be greater than or equal too 100.

8n+5b ≥ 100

3 0

3 years ago

Question in the picture!

Sunny_sXe [5.5K]

Answer:

x = 12

Step-by-step explanation:

Vertical angles are congruent, so ...

4x = 48°

x = 12° . . . . . . divide by 4

8 0

3 years ago

What do you predict the solution for the system 5x-6y=7 and 6x-7y=8 will be ?<br>

Alenkinab [10]

System of Linear Equations entered :

[1] 5x - 6y = 7
[2] 6x - 7y = 8
Graphic Representation of the Equations :

-6y + 5x = 7 -7y + 6x = 8

Solve equation [2] for the variable x

[2] 6x = 7y + 8

[2] x = 7y/6 + 4/3
// Plug this in for variable x in equation [1]

[1] 5•(7y/6+4/3) - 6y = 7
[1] - y/6 = 1/3
[1] - y = 2
// Solve equation [1] for the variable y

[1] y = - 2
// By now we know this much :

x = 7y/6+4/3
y = -2
// Use the y value to solve for x

x = (7/6)(-2)+4/3 = -1

8 0

3 years ago