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Sloan [31]
3 years ago
5

An electrical power company is looking to expand into a new market. Before they commit to supplying the new area with electricit

y, they would like know the mean daily power usage for homes there. However, measuring the daily power usage of every home is not practical. Thus, an experiment must be designed where a sample of homes will have their daily power usage measured. Determine the required sample size to ensure that the 95% confidence interval for the population mean daily power usage is not larger than ±5 kWh. That is, determine the minimum sample size such that the error between the sample mean �" and population mean µ does not exceed 5 kWh, with 95% confidence. Based on historical trends, the population standard deviation can safely be assumed to be 50 kWh.
Mathematics
1 answer:
TiliK225 [7]3 years ago
5 0

Answer:

atleast 385

Step-by-step explanation:

Given that an electrical power company is looking to expand into a new market. Before they commit to supplying the new area with electricity, they would like know the mean daily power usage for homes there.

Population std deviation = \sigma = 50

Sample size =n

STd error of sample mean = \frac{50}{\sqrt{n} }

Margin of error for 95% would be Critical value ( std error)

Here since population std dev is known we can use Z critical value= 1.96

1.96*\frac{50}{\sqrt{n} }19.6^2\\n>384.16

Sample size should be atleast 385

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Explanation

To find the triangle is acute, obtuse or right triangle.

To determine whether the triangle is acute, right, or obtuse.add the squares of the two smaller sides, and compare the sum to the square of the largest side. Since this sum is greater, the triangle is acute.

A

If the sum of the squares of the two smaller sides is equal to the square of the largest side , then it is right triangle.

Now c.

\begin{gathered} 30^2=24^2+18^2 \\ 900=576+324 \\ 900=900 \end{gathered}

Answer

Hence the sum of the squares of the two smaller sides is equal to the square of the largest side , then it is right triangle.

The correct option is A.

3 0
1 year ago
The roots of an equation are x=-1 plus or minus I the equation is x^2+ ?
Oxana [17]

Answer:

x^2+2x+2

Step-by-step explanation:

If the roots of the equation are -1\pm i, then by the zero product rule:

x=-1\pm i \\\\x+1\pm i=0 \\\\(x+1+i)(x+1-i)=0\\\\x^2+x-ix+x+1-i+ix+i+1=0 \\\\x^2+2x+2=0

You can confirm this with the quadratic equation:

x=\dfrac{-2\pm\sqrt{4-8}}{2}=\dfrac{-2\pm 4i}{2}=-1\pm i

Hope this helps!

8 0
2 years ago
Huddson has practiced a 360-back flip for months. This week, he did it perfectly 24 out of 54 times. At this rate, how many time
iris [78.8K]
Let x = perfect flips out of nine
\frac{24}{54}  =  \frac{x}{9}
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4 flips
5 0
3 years ago
Find the solution of this system of equations. Separate the x- and y-values with a comma. x - 4y = 12 and x - y = 0
Elenna [48]
Use elimination and subtitution method to solve the problem.
First, eliminate x and you'll find the value of y
x - 4y = 12
x -  y  = 0
--------------- - (substract)
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        y = 12/-3
        y = -4

Second, subtitute -4 as y and you'll find the value of x
x - y = 0
x- (-4) = 0
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The solution
x,y = -4,-4
6 0
3 years ago
The yearbook committee polled 80 randomly selected students from a class of 320 ninth graders to see if they would be willing to
jek_recluse [69]

Answer:

The margin of error is given below:

E=z \times \sqrt{\frac{\hat{p}(1-\hat{p}}{n} }

Where:

\hat{p}=\frac{26}{80}=0.325

\therefore E = z \times \sqrt{\frac{0.325(1-0.325}{80} }

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Therefore, the option E = z*6% is correct as it closest to the given answer

7 0
2 years ago
Read 2 more answers
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