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3 years ago

X+2y=12 3x-10y = 0 y=? x=?

2 answers:

8 0

$x+2y=12|\cdot5\\
3x-10y=0\\\\
5x+10y=60\\
\underline{3x-10y=0}\\
8x=60\\
x=\dfrac{60}{8}=\dfrac{15}{2}\\\\
\dfrac{15}{2}+2y=12\\
15+4y=24\\
4y=9\\
y=\dfrac{9}{4}\\\\
\boxe{(x,y)=\left(\dfrac{15}{2},\dfrac{9}{4}\right)}$

sergeinik [125]3 years ago

3 0

$~~x+2y=12 \\ ~~3x-10y=0 \\
~------ \\~ -3/x+2y=12 \\ ~~~~~~3x-10y=0 \\ ------- \\ -3x-6y=-36 \\ ~~~~3x-10y=0 \\ +------- \\ ~~~~-16y=-36 \\ \\ ~~~~y= \frac{36}{16}\rightarrow \boxed{\frac{9}{4}} \\ \\$
$x+2. \frac{9}{4} =12 \\ \\ x+ \frac{18}{4} =12 \\ \\ \frac{4x+18}{4} =12 \\ \\ 4x+18=48 \\ 4x=30 \\ \\ x=\boxed{\frac{15}{2}}$

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a major metroplitan newspaper selected a simple random sample of 1,600 readers from their list of 100,000 subscribers. they aske

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Answer:

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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.

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

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

For this problem, we have that:

$n = 1600, \pi = 0.4$

99% confidence level

So $\alpha = 0.01$ , z is the value of Z that has a pvalue of $1 - \frac{0.01}{2} = 0.995$ , so $Z = 2.575$ .

The lower limit of this interval is:

$\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.4 - 2.575\sqrt{\frac{0.4*0.6}{1600}} = 0.3685$

The upper limit of this interval is:

$\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.4 + 2.575\sqrt{\frac{0.4*0.6}{1600}} = 0.4315$

The 99% confidence interval for the proportion of readers who would like more coverage of local news is (0.3685, 0.4315).

7 0

3 years ago

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nekit [7.7K]

Answer:

10ft

Step-by-step explanation:

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3 years ago

Jillian's puppy weighed 16 pounds at the age of 2 months. It weighed 60 pounds at the age of 8 months. What is the percent chang

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Answer:the percent change in the puppy's weight= 275%

Step-by-step explanation:

Jillian's puppy Weight at 2 months =16 pounds

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3 years ago

(2x+y=-2<br> 5x + 3y = -8<br> Solve by elimination

Effectus [21]

Answer:

y = -6, x =2

Step-by-step explanation:

To solve by elimination, you have to line both equations up together. Then, you multiply both equations until one variable is removed.

2x+y = -2

5x + 3y = - 8

There are many different ways to solve an elimination problem, but generally you should look for the simplest route. Here, I would multiply the top equation by -3.

-6x -3y = 6

5x +3y = -8

Imagine you are adding the two equations together. You end up with

-x = -2

Then solve for x. In this situation, it is fairly simple. Take out a factor of -1.

x = 2

Finally, choose one of your beginning equations and plug your new-found x value back into the equation.

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3 years ago

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Answer:

20% gained

Step-by-step explanation:

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6 0

2 years ago