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2 years ago

What is the result of adding these two equations?

Mathematics

1 answer:

Marina86 [1]2 years ago

7 0

Answer:

-2x-7y=-4

Step-by-step explanation:

We want to add the two expressions

$\begin{aligned} 5x-9y &= 1 \\ -7x+2y &= -5 \end{aligned}$

First we add the Left Hand Sides and do the same to the Right Hand Sides. This gives us:

(5x-9y)+(-7x+2y)= 1 +( -5)

Open the brackets

5x-9y-7x+2y=1-5

Regroup like terms

5x-7x-9y+2y=-4

-2x-7y=-4

The result of adding the two given expressions is -2x-7y=-4.

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The population standard deviation for the typing speeds for secretaries is 4 words per minute. If we want to be 90% confident th

Oksana_A [137]

Answer:

The minimum sample size that should be taken is 62.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.9}{2} = 0.05$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.05 = 0.95$ , so $z = 1.645$

Now, find the margin of error M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

If we want to be 90% confident that the sample mean is within 1 word per minute of the true population mean, what is the minimum sample size that should be taken

This is n when $M = 1, \sigma = 4$ . So

$M = z*\frac{\sigma}{\sqrt{n}}$

$1 = 1.96*\frac{4}{\sqrt{n}}$

$\sqrt{n} = 4*1.96$

$(\sqrt{n})^{2} = (4*1.96)^{2}$

$n = 61.5$

The minimum sample size that should be taken is 62.

8 0

3 years ago

Pls help!! 25 points!!

ankoles [38]

Answer:

(6, 840) (5, 700) (3, 420) (4, 560)

Step-by-step explanation:

Use the one point that is completely filled out, (6, 840). Divide 840 by 6 and you get 140 so that is the slope. 5x140= what the y intercept will be, 700. 420/140= what the x intercept will be, 3. Now you can see a pattern which helps check your work. They are all decreasing pretty much, not really ordered much but. And finally the last point 4x140=560. Hope that helps! :)

4 0

2 years ago

Answer it answer it answer it

AysviL [449]

Answer: D.

Step-by-step explanation: If you look closely, putting a 100 wouldn't make sense

6 0

3 years ago

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Sixty percent of the students at a certain school wear neither a ring nor a necklace. Twenty percent wear a ring and 30 percent

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