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3 years ago

What is the simplified form of this expression?

Mathematics

1 answer:

tankabanditka [31]3 years ago

3 0

Answer:

The answer is A

Step-by-step explanation:

here you go mate'

Step 1

(8x - 7) + (-2x - 9) - (4x - 3) equation

step 2

(8x - 7) + (-2x - 9) - (4x - 3) expand by distributing

8x+-7+-2x+-9+-4x+3

step 3

8x+-7+-2x+-9+-4x+3 combine terms

answer

2x-13

can i get brainliest if you dont mind?

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23. A certain type of gasoline is supposed to have a mean octane rating of at least 90. Suppose measurements are taken on of 5 r

Nostrana [21]

Answer:

a) $p_v =P(Z$

b) Since $p_v$ we can reject the null hypothesis at the significance level given. So based on this we can commit type of Error I.

Because Type I error " is the rejection of a true null hypothesis".

c) $P(\bar X >90)=1-P(Z$

$1-P(Z$

d) For this case we need a z score that accumulates 0.02 of the area on the right tail and 0.98 on the left tail and this value is z=2.054

And we can use this formula:

$2.054=\frac{90-89}{\frac{0.8}{\sqrt{n}}}$

And if we solve for n we got:

$n = (\frac{2.054 *0.8}{1})^2=2.7 \approx 3$

Step-by-step explanation:

Previous concepts and data given

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".

We can calculate the sample mean and deviation with the following formulas:

$\bar X = \frac{\sum_{i=1}^n X_i}{n}$

$s=\sqrt{\sum_{i=1}^n (X_i -\bar X)^2}{n-1}$

$\bar X=88.96$ represent the sample mean

$s=1.011$ represent the sample standard deviation

n=5 represent the sample selected

$\alpha$ significance level

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the mean is less than 90, the system of hypothesis would be:

Null hypothesis: $\mu \geq 90$

Alternative hypothesis: $\mu < 90$

If we analyze the size for the sample is < 30 and we don't know the population deviation so is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:

$z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}$ (1)

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic

We can replace in formula (1) the info given like this:

$z=\frac{88.96-90}{\frac{0.8}{\sqrt{5}}}=-2.907$

Part a

P-value

First we need to calculate the degrees of freedom given by:

$df=n-1=5-1 = 4$

Then since is a left tailed test the p value would be:

$p_v =P(Z$

Part b

Since $p_v$ we can reject the null hypothesis at the significance level given. So based on this we can commit type of Error I.

Because Type I error " is the rejection of a true null hypothesis".

Part c

We want this probability:

$P(\bar X$

The best way to solve this problem is using the normal standard distribution and the z score given by:

$z=\frac{x-\mu}{\frac{\sigma}{\sqrt{n}}}$

If we apply this formula to our probability we got this:

$P(\bar X >90)=1-P(Z$

$1-P(Z$

Part d

For this case we need a z score that accumulates 0.02 of the area on the right tail and 0.98 on the left tail and this value is z=2.054

And we can use this formula:

$2.054=\frac{90-89}{\frac{0.8}{\sqrt{n}}}$

And if we solve for n we got:

$n = (\frac{2.054 *0.8}{1})^2=2.7 \approx 3$

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3 years ago

Which one should I be picking??

tensa zangetsu [6.8K]

Answer:

angle 1 is 39

angle 3 is 51

Step-by-step explanation:

Here, we want to get the value of angle 1 and angle 3

Let’s have the meeting point of the diagonals as E

Hence , ADE is a right triangle

Thus,

39 + angle 3 = 90

angle 3 = 90-39

angle 3 = 51

Furthermore;

we can see that ABD is isosceles, meaning that the base angles are equal

Thus, we have it that;

angle 3 and angle at B (for AEB triangle) are equal in values

So, we can conclude that the angle is 51 too

so if the angle is 51 too, then the triangles ADE and ABE are similar

That simply means angle marked 1 is 39

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PQ is tangent to OR at point P. Find mZQ. A. 17° B. 27° C. 63° D. 73°

mamaluj [8]

Answer:

Step-by-step explanation:

The angle between the tangent PQ and the radius RP at the point of contact P is 90°

The sum of the 3 angles in Δ PQR = 180° , thus

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Answer: A. (72π - 144) mm²

Step-by-step explanation:

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