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Kitty [74]
3 years ago
14

Two lines, A and B, are represented by the equations given below!

Mathematics
1 answer:
lara [203]3 years ago
8 0

Answer:

The solutions to the system of equations are:

y=-8,\:x=-4

Thus, option C is true because the point satisfies BOTH equations.

Step-by-step explanation:

Given the system of the equations

\begin{bmatrix}y=x-4\\ y=3x+4\end{bmatrix}

Arrange equation variables for elimination

\begin{bmatrix}y-x=-4\\ y-3x=4\end{bmatrix}

y-3x=4

-

\underline{y-x=-4}

-2x=8

\begin{bmatrix}y-x=-4\\ -2x=8\end{bmatrix}

solve for x

-2x=8

Divide both sides by -2

\frac{-2x}{-2}=\frac{8}{-2}

x=-4

\mathrm{For\:}y-x=-4\mathrm{\:plug\:in\:}x=-4

y-\left(-4\right)=-4

y+4=-4

y=-8

The solutions to the system of equations are:

y=-8,\:x=-4

Thus, option C is true because the point satisfies BOTH equations.

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In order to ensure efficient usage of a server, it is necessary to estimate the mean number
juin [17]

Answer:

a. [36.19;39.21]

b. Reject the null hypothesis. The population mean of users that are connected at the same time is greater than 35.

Step-by-step explanation:

Hello!

Your study variable is,

X: "number of users of one server at a time"

The objective is to estimate the mean, for this, a sample of n=100 times was taken and the standard deviation S= 9.2 and the sample mean is X[bar]= 37.7 were calculated.

You need to study the population mean, for this you need your variable to have at least normal distribution. Since you don't have information about its distribution, but the sample is big enough (n≥30) you can apply the Central Limit Theorem and approximate the distribution of the sample mean X[bar] to normal:

X[bar]≈N(μ;σ²/n)

a. With this approximation, you can construct the 90% Confidence Interval using the approximate Z

[X[bar] ± Z_{1-\alpha /2} * S/√n]

Z_{1-\alpha /2} = Z_{0.95} = 1.64

[37.7± 1.64* 9.2/√100]

[36.19;39.21]

b. You need to test if the population mean is greater than 35 with a level of significance of 1%.

The hypothesis is:

H₀: μ ≤ 35

H₁: μ > 35

α: 0.01

This is a one-tailed test so you have only one critical level (right tail):

Z_{1\alpha } = Z_{0.99} = 2.33

This means that if the value of the calculated statistic is equal or greater than 2.33 you will reject the null Hypothesis.

If the value is less than 2.33 you will support the null hypothesis.

The statistic is:

Z=<u> X[bar] - μ </u>= <u> 37.7 - 35 </u> = 2.93

       S/√n           9.2/10

The value 2.93 > 2.33, so you reject the null hypothesis. This means that the population mean of users that are connected at the same time is greater than 35.

<u><em>Note: </em></u><em>To make the decision using the interval calculated on a), the hypothesis should have been two-tailed and the confidence and significance levels complementary.</em>

I hope it helps!

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3 years ago
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Rashid [163]

Answer:

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Step-by-step explanation:

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Find the median if this set of numbers: 7, 6, 19, 12, 16, 19, 19, 6 ​
tankabanditka [31]

Answer:

20

Step-by-step explanation:

Order the numbers from smallest to largest, then cross one number off until you have one or two numbers left.

If there is an EVEN number of numbers(like this one): there will be two numbers left, therefore you add those two numbers together, then divide by two.

If there is  an ODD number of numbers: there will be one number left, therefore that is your answer!

Hope this helps!

-PusheenDaCat1017

6 0
3 years ago
Enter the range of values for x:<br> 2x - 4<br> 10<br> 45<br> 60<br> 2
Yakvenalex [24]

Step-by-step explanation:

hope this will help you.

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3 years ago
Read 2 more answers
Sociology graduates, upon entering the workforce are normally distributed and earn a mean salary of $30,000 with a standard devi
GrogVix [38]

Answer:

0.62% probability that randomly chosen salary exceeds $40,000

Step-by-step explanation:

Problems of normally distributed distributions are solved using the z-score formula.

In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

Z = \frac{X - \mu}{\sigma}

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this question:

\mu = 30000, \sigma = 4000

What is the probability that randomly chosen salary exceeds $40,000

This is 1 subtracted by the pvalue of Z when X = 40000. So

Z = \frac{X - \mu}{\sigma}

Z = \frac{40000 - 30000}{4000}

Z = 2.5

Z = 2.5 has a pvalue of 0.9938

1 - 0.9938 = 0.0062

0.62% probability that randomly chosen salary exceeds $40,000

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