The amount people who pay for electric service varies quite a bit, but the mean monthly fee is $168 and the standard deviation i
s $34. The distribution is not Normal. Many people pay about $90 in rural areas of the country and about $150 in urban areas of the country, but some pay much more. A sample survey is designed to ask a simple random sample of 1,200 people how much they pay for electric services. Let xbar be the mean amount paid. Part A: What are the mean and standard deviation of the sample distribution of xbar? Show your work and justify your reasoning. (4 points) Part B: What is the shape of the sampling distribution of xbar? Justify your answer. (2 points) Part C: What is the probability that the average electric service paid by the sample of electric service customers will exceed $170? Show your work. (4 points)
1 answer:
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Answer: Choice C
Graph with filled in circles at d = 0 and d = 2, shading in between
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Explanation:
d = amount downloaded in gigabytes
The smallest amount is d = 0. We cannot download a negative amount of data, so this is why d = 0 is the smallest.
The largest amount allowed is d = 2. This is the cap that the ISP has set up.
So basically d can be anything between d = 0 and d = 2, including both endpoints. This means
We use filled in circles for both endpoints to show to the reader "include these endpoints". Shading is done in between to show the entire solution set of possible d values. For instance d = 1 is in that region so it is possible to have this solution. Something like d = 4 is outside the region and not possible.
I have included a picture. In the picture you will find the work and final answer.
