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    Solving for Point Estimates and Confidence Intervals

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    Question: The Warren County Telephone Company claims in its annual report that "the typical customer spends $70 per month on local and long-distance service." A sample of 12 subscribers revealed the following amounts spent last month.

    Amounts Spent Last Month:
    $64
    $57
    $59
    $68
    $60
    $65
    $69
    $56
    $58
    $56
    $55
    $56

    (a) What is the point estimate of the population mean? (Round your answer to 3 decimal places)
    (b) Determine the 99% confidence interval for the population mean. (Round your answer to 2 decimal places)
    Note: Confidence interval is between $ and $.
    (c) Is the company's claim that the "typical customer" spends $70 per month reasonable?

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    https://brainmass.com/statistics/confidence-interval/solving-point-estimates-confidence-intervals-514952

    Solution Preview

    Hi there, here is my explanation:

    a) mean=(64+57+59+68+60+65+69+56+58+56+55+56)/12=60.250

    b) Since n=12<30, we need to use a t ...

    Solution Summary

    The solution gives a few lines' calculations for each part with some worded explanation.

    $2.19

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