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klasskru [66]
3 years ago
10

A skateboard ramp has a slope of 4/9. What is the measure of the angle the ramp forms with the ground

Mathematics
1 answer:
Mama L [17]3 years ago
7 0

Answer:

Step-by-step explanation:

tanθ = 4/9

θ = arctan(4/9) ≈ 23.96°

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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
Place decimal points in 34, 4, and 417 so that the sum of the three numbers is 7.97.
KIM [24]
3.4+0.4+4.17=7.97 you just have to try different combinations of different numbers with the decimals.
                                                             





8 0
3 years ago
the width of a rectangle is 2 units less than the length. the area of the rectangle is 63 units.what is the length, in units, of
Mice21 [21]

Answer: 9

Step-by-step explanation:

3 0
2 years ago
A day-care center has 2 baskets of dolls. One basket has 8 dolls, and the other basket has an unknown number of dolls in it. Wha
xenn [34]

Answer:

d+8

Step-by-step explanation:

Let d represent number of dolls in 2nd basket.

We have been given that a day-care center has 2 baskets of dolls. One basket has 8 dolls, and the other basket has an unknown number of dolls in it. We are asked to represent this situation in an expression.

The number in both baskets would be equal to dolls in 1st basket plus dolls in 2nd basket.

We can represent this information in an expression as:

d+8

Therefore, our required expression would be d+8, where d represents number of dolls in 2nd basket.

3 0
3 years ago
Please help me!!!!!!!!
bekas [8.4K]

Step-by-step explanation:

might be option c is a correct answer of your given question

4 0
3 years ago
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