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3 years ago

PLEAAASE HELP ILL MARK BRAINLIEST

Mathematics

2 answers:

kicyunya [14]3 years ago

8 0

Answer:

The answer is 69

Step-by-step explanation:

You have to substitute y by 9 and by 3

Jet001 [13]3 years ago

8 0

Answer:

Step-by-step explanation:

Since y is equal to 9 and z is equal to 3, we do 10 x 9 - 7 x 3. 10 times 9 is 90, and 7 times 3 is 21.

Then, we do 90-21. 90-21=69. Therefore, 10y-7z = 69.

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A rectangular red sticker is 8 millimeters wide and 5 millimeters tall. What is it’s area

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40 milimeters

Step-by-step explanation:

8*5=40

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You are a sports writer watching a baseball game. The picture is thrown a fastball, a curveball, then to fast balls, and two cur

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The answer is C, C, C, C, F

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2 years ago

In the diagram, a circle centered at the origin, a right triangle, and the Pythagorean theorem are used to derive the equation o

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(x – h)2 + (y – k)2 = r2

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5 0

3 years ago

Read 2 more answers

Draw and label a rectangular prism that has a surface area of 96 square meters.

Mashcka [7]

Basically what you need to do is draw 4 congruent rectangles and 2 comgriemt squares (The six sides of a rectangular prism). The sum of the area of these six quadrilaterals should equal 96. This would be my thought process.

Step 1: Sketch a Rectangular Prism

Step 2: Make some educated guesses on some possible side measurements for the quadrilaterals that form the prism.

Step 3: Guess and Check until the amount equals 96.

So we can guess that the sides of the rectangle might equal 2 and 3 units.

This would be 6 for the area. Times 4 for each of the 4 Rectangles. (24) and add the area of the ends of the prism (2*2*2) which is 8 and you will get 32.

Since we are looking for a surface area of 96 and not 32, we can assume that a 3*2*2 prism is not what we need. So we can try again with other values.

Let's try 6*3*3. 6*3*4 for the four rectangles plus 3*3*2 for the ends.

3 0

3 years ago

Assume that the helium porosity of coal samples taken from any particular seam is Normally distributed with true standard deviat

riadik2000 [5.3K]

Answer:

a) $4.85-2.33\frac{0.75}{\sqrt{20}}=4.46$

$4.85+2.33\frac{0.75}{\sqrt{20}}=5.24$

b) $4.56-2.33\frac{0.75}{\sqrt{16}}=4.12$

$4.56+2.33\frac{0.75}{\sqrt{16}}=4.99$

c) $n=(\frac{1.960(0.75)}{0.2})^2 =54.02 \approx 55$

Step-by-step explanation:

Part a

The confidence interval for the mean is given by the following formula:

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

The Confidence is 0.98 or 98%, the value of $\alpha=0.02$ and $\alpha/2 =0.01$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.01,0,1)".And we see that $z_{\alpha/2}=2.33$

Now we have everything in order to replace into formula (1):

$4.85-2.33\frac{0.75}{\sqrt{20}}=4.46$

$4.85+2.33\frac{0.75}{\sqrt{20}}=5.24$

Part b

$4.56-2.33\frac{0.75}{\sqrt{16}}=4.12$

$4.56+2.33\frac{0.75}{\sqrt{16}}=4.99$

Part c

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 =0.4/2 =0.2 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)

The critical value for 95% of confidence interval now can be founded using the normal distribution. And in excel we can use this formla to find it:"=-NORM.INV(0.025;0;1)", and we got $z_{\alpha/2}=1.960$ , replacing into formula (b) we got:

$n=(\frac{1.960(0.75)}{0.2})^2 =54.02 \approx 55$

5 0

3 years ago