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Nina [5.8K]
3 years ago
7

In 2014, 85 percent of households in the United States had a computer. For a randomly selected sample of 200 households in 2014,

let the random variable C represent the number of households in the sample that had a computer. What are the mean and standard deviation of C ?
Mathematics
2 answers:
DochEvi [55]3 years ago
7 0

Answer:

The mean of C is 170 households

The standard deviation of C, is approximately 5 households

Step-by-step explanation:

The given parameters are;

The percentage of households in the United States that had a computer in 2014 = 85%

The size of the randomly selected sample in 2014, n = 200

The random variable representing the number of households that had a computer = C

Therefore, we have;

The probability of a household having a computer P = 85/100 = 0.85

Let

Therefore;

The mean (expected) number in the sample, μₓ, = E(x) = n × P is given as follows;

μₓ = 200 × 0.85 = 170

The mean of C = μₓ = 170

The variance, σ² = n × P × (1 - P) = 200 × 0.85 × (1 - 0.85) = 25.5

Therefore;

The standard deviation, σ = √(σ²) = √(25.5) ≈ 5.05

The standard deviation of C, σ ≈ 5 households (we round (down) to the nearest whole number)

pickupchik [31]3 years ago
5 0

Answer:

The mean is 170 households, and the standard deviation is 5.05 households.

Step-by-step explanation:

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<u>QUESTION 18</u>

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\left[\begin{array}{ccc}a&b\\c&d\\\end{array}\right] *\left[\begin{array}{ccc}x\\y\\\end{array}\right] = \left[\begin{array}{ccc}ax&by\\cx&dy\\\end{array}\right]

Once you get that final matrix, you add the rows which will give you a final column vector. Let's do it with this question, as we are multiplying together the matrices A and v.

\left[\begin{array}{ccc}-1&4\\2&0\\\end{array}\right] *\left[\begin{array}{ccc}8\\6\\\end{array}\right] =\left[\begin{array}{ccc}-8&24\\16&0\\\end{array}\right] =\left[\begin{array}{ccc}16\\16\\\end{array}\right]

So, your answer is \left[\begin{array}{ccc}16\\16\\\end{array}\right].

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<u>QUESTION 14</u>

We have this equation of an ellipse and we need to solve for y. When we have a more complex equation to solve you get rid of the things furthest from the variable you are solving for first and then you get closer and closer to it.

\frac{x^2}{25} + \frac{y^2}{16}=1

We subtract \frac{x^2}{25} from both sides.

\frac{y^2}{16}=1-\frac{x^2}{25}

We multiply both sides by 16.

y^2=1-\frac{x^2}{25}*16

We square root both sides.

y= \sqrt{1-\frac{x^2}{25}*16

We can take a four out of our root (because 16 is a perfect square so it can be simplified more).

y= 4\sqrt{1-\frac{x^2}{25}

And we take out 1/5 (which is the square root of 1/25).

y=± \frac{4}{5}\sqrt{1-x^2

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<u>QUESTION 17</u>

We see that Sea Slugs have 3/10 matches won, so they have won 30% of their matches.

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<u>QUESTION 16</u>

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<u>QUESTION 12</u>

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Have a wonderful day and keep on learning! :D

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Answer:

<u>Graph of the equation y = 2/5x - 1</u>

Please check the attached graph of the equation where:

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Step-by-step explanation:

Given the equation

y = 2/5x - 1

<u>Determining the y-intercept:</u>

We know that the value of the y-intercept can be determined by setting x = 0 and determining the corresponding value of y.

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We know that the value of the x-intercept can be determined by setting x = y and determining the corresponding value of x.

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<u>Graph of the equation y = 2/5x - 1</u>

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The point  (2.5, 0) represents the x-intercept, it is the point where the line crosses the x-axis.

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