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ella [17]
3 years ago
7

Simplify 1/2b^- 3 please help

Mathematics
1 answer:
11Alexandr11 [23.1K]3 years ago
5 0

 \frac{3b^{2}}{4}  

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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

Assuming that the deviation is known we can express the margin of error is given by this formula:

ME=z_{\alpha/2}\frac{\sigma}{\sqrt{n}}    (a)

And on this case we have that ME =\pm 3 and we are interested in order to find the value of n, if we solve n from equation (a) we got:

n=(\frac{z_{\alpha/2} \sigma}{ME})^2   (b)

Replacing into formula (b) we got:

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

8 0
3 years ago
Two angles are complementary. The measure of ∠ABC is x° and the measure of ∠DBC is (3x + 10)°. What is the value of x?
beks73 [17]
42.5 I think

3x+10+x=180
4x=170
170/4=x
X=42.5
5 0
2 years ago
Read 2 more answers
What’s the answer please??
damaskus [11]

Answer:

The answer is C

Step-by-step explanation:

Straight angles means a line which straight and has no turning.

5 0
3 years ago
Read 2 more answers
How to solve for the answer
yarga [219]
A.step 1 because it should be x^2 not 2x
3 0
3 years ago
Which statements are true?
iVinArrow [24]

Answer:

this made no sense at first but the answer is b

Step-by-step explanation:

8 0
2 years ago
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