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3 years ago

What is -3x+5y=-2 2x-2y=1

1 answer:

4 0

<span><span>Solve equation 2 for x:
2x - 2y = -12
2x = 2y -12
x = y - 6
.
Using the above definition of x, we plug it in to equation 1 and solve for y:
2x + 5y = 2
2(y - 6) + 5y = 2

2y - 12 + 5y = 2
7y - 12 = 2
7y = 14
y = 2
.
Plug the above back into equation 2 and solve for x:
2x - 2y = -12
2x - 2(2) = -12
2x - 4 = -12
2x = -8
x = -4
.
Solution:
x = -4
y = 2</span></span>

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Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

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a. If a 95% confidence interval with a margin of error of no more than 0.04 is desired, give a close estimate of the minimum sample size that will guarantee that the desired margin of error is achieved. (Remember to round up any result, if necessary.)

This is n for which M = 0.04. So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

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$0.04\sqrt{n} = 1.96*0.5$

$\sqrt{n} = \frac{1.96*0.5}{0.04}$

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The minimum sample size is 601.

b. If a 95% confidence interval with a margin of error of no more than 0.02 is desired, give a close estimate of the minimum sample size necessary to achieve the desired margin of error.

Now we want n for which M = 0.02. So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.02 = 1.96\sqrt{\frac{0.5*0.5}{n}}$