Helpmeeee please!!!!!

Factor the following polynomial completely. x²n - y²n

Alekssandra [29.7K]

Answer:

(n)*(x+y)(x-y)

Step-by-step explanation:

First of all, you take the n out, and then you use the formula of x²- y² and it will equal to (x+y)(x-y).

8 0

2 years ago

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Mabel spends 444 hours to edit a 333 minute long video. She edits at a constant rat\\\\\\\\\\\\\\e. How long does Mabel spend to

mestny [16]

Mabel spends 4 hours editing a 3 minute video. she edits at a constant rate. how long does mabel spend to edit a 9 minute video?

she spends 4 hours on a 3 minute video
so there are 60 minutes in an hour
4 hours with 60 minutes- 4x60=240
so she spent 240 minutes on a 3 minute video
3 divided by 240
3/240= 0.0125
so her constant rate is 0.0125 minutes an hour
so divide 9 minutes by her constant rate
9/0.0125 = 720
so she spends 720 minutes on a 9 minute video.
divide 720 by 60 since there are 60 minutes in an hour
720/60 = 12
so she spends 12 hours on a 9minute video

7 0

2 years ago

A doctor wants to estimate the mean HDL cholesterol of all 20- to 29-year-old females. The number of subjects needed to estima

Ludmilka [50]

Answer:

$n=(\frac{1.64(14.7)}{3})^2 =64.57 \approx 65$

So the answer for this case would be n=65 rounded up to the nearest integer

And the sample size would decrease by 160-65=95 subjects

Step-by-step explanation:

1) 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".

$\bar X$ represent the sample mean for the sample

$\mu$ population mean (variable of interest)

s represent the sample standard deviation

n represent the sample size

ME represent the margin of error

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

2) Solution to the problem

Since the new Confidence is 0.90 or 90%, the value of $\alpha=0.1$ and $\alpha/2 =0.05$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.05,0,1)".And we see that $z_{\alpha/2}=1.64$