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Oksana_A [137]
3 years ago
9

In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determi

ned. Assume a population standard deviation of 450 kilowatt-hours. If the sample mean is 1858 kWh, the 95% confidence interval estimate of the population mean is
Mathematics
1 answer:
lana [24]3 years ago
6 0

Answer:

Confidence interval:  (1760,1956)

Step-by-step explanation:

We are given the following information in the question:

Sample size, n = 81

Sample mean =

\bar{x} = 1858 \text{ kWh}

Population standard deviation =

\sigma = 450 \text{ kilowatt-hours}

Confidence Level = 95%

Significance level = 5% = 0.05

Confidence interval:

\bar{x} \pm z_{critical}\displaystyle\frac{\sigma}{\sqrt{n}}

Putting the values, we get,

z_{critical}\text{ at}~\alpha_{0.05} = \pm 1.96

1858 \pm 1.96(\displaystyle\frac{450}{\sqrt{81}} ) = 1858 \pm 98 = (1760,1956)

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wolverine [178]

Answer:

There are 210 students running track and 98 students that play baseball.

Step-by-step explanation:

15*14= 210 and 7*14 = 98, 210 - 98 = 112. If this was correct feel free to mark me as brainiest :)

4 0
3 years ago
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Answer:

1) A

2) C

Step-by-step explanation:

The range is all real y values, in this case it includes zero and continues going downward towards negative infinity.

The domain is all real x values. In this case it includes zero and continues increasing to positive infinity.

Hope this helps!

5 0
3 years ago
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Margarita [4]
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Vera_Pavlovna [14]

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Brilliant_brown [7]
Standard form of a circle is (x-h)²+(y-k)²=r², (h, k) being the center, r the radius.
In this case, (x-h)²+(y-k)²=16
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You can also set k=1, h=-3 or 5
Note: there are many other possibilities. 
4 0
3 years ago
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