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4 years ago

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A cattle rancher has 2600ft of fencing that will be used to enclose a rectangular feed lot. If one of the dimensions of tge feed

lot is x, find a formula for the area y of the feed lot(in square feet) as a function of x

1 answer:

tresset_1 [31]4 years ago

4 0

650 ft ×4= 2600 square ft

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What is the volume of the right prism?

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We know that:
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3 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

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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

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3 years ago

Jazelle Momba wants to visit her family in Zimbabwe in 2025, which is 6 years from now. She knows that it will cost approximatel

Ludmilka [50]

9514 1404 393

Answer:

$6307.95

Step-by-step explanation:

The compound interest formula can help with that.

A = P(1 +r/n)^(nt) . . . . value of principal P at rate r for t years, compounded n times per year.

P = A(1 +r/n)^(-nt) = $8000(1 +0.04/2)^(-2·6) = $8000(1.02^-12) = $6307.95

Momba needs to deposit $6307.95 today to have $8000 in 6 years.

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3 years ago