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3 years ago

PLEASE HELP ME ASAP ITS TIMED

Mathematics

1 answer:

WINSTONCH [101]3 years ago

3 0

Answer:

The solution is (2, 1).

All other ordered pairs do not work.

Step-by-step explanation:

-2x + 5y = 1

5x - 3y = 7

-10x + 25y = 5

10x - 6y = 14

19y = 19

y = 1

5x - 3(1) = 7

5x = 10

x = 2

(2, 1)

The solution is (2, 1).

All other ordered pairs do not work.

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Explanation:

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To go from (-7,0) to (-3,-1), we will do two things

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This can be done in any order. The action of "shift 4 units to the right" is effectively the same as shifting the xy axis 4 units to the left while keeping the curves fixed in place. This gives the illusion of movement. When we shift 4 the xy axis 4 units to the left, we're replacing each x input with x-4 as the new input.

In short, we go from f(x) to f(x-4). This is why we have this opposite motion going on.

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3 years ago

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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

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Answer:

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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 $z_{\alpha/2}=1.64$