Please answer ALL question or some ASAP

It takes Dariya 35 seconds to download 5 songs from the Internet. How can the number of seconds it would take Dariya to download

Alex73 [517]

By finding the unit rate and multiplying it by 7

8 0

3 years ago

Read 2 more answers

Use the compound interest formula to find the present value P, for the following given values.

Nookie1986 [14]

The question is not valid

3 0

3 years ago

What's the answer for 3/4 (x+3)=9

Vitek1552 [10]

We want to solve the equation :

$\displaystyle{ \frac{3}{4}(x+3)=9$

first, multiply both sides by 4:

$\displaystyle{ \cancel{4} \cdot \frac{3}{ \cancel 4 }(x+3)=4\cdot 9$

$\displaystyle{ 3(x+3)=36$

divide both sides by 3:

$x+3=12$

add -3 to both sides:

$x=9$

Answer: x=9

3 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

Anna walks at a constant rate of 8 miles every 2 hours Graph a line to show the relationship between the time in hours, 1 and th

stiks02 [169]

Answer:

We see that the only complete time-distance pair indicates that she walked 6.4 miles in 2 hours. If she walked at a constant speed, we can conclude that girl walked 3.2 miles in 1 hour. Using this speed, we can find the remaining values in the table. The easier entry to complete is finding out how far she walked in 5 hours: 5 hours⋅3.2 miles/hour=16 miles. To find out how long it took to walk 8 hours we can either notice that 8 is half of 16, so it took half the time to walk half the distance or we can divide 8 miles by 3.2 miles per hour to find that it took 2.5 hours

Step-by-step explanation:

8 0

3 years ago