Warren County Telephone Company claims in its annual report that “the typical cu
ID: 3261800 • Letter: W
Question
Warren County Telephone Company claims in its annual report that “the typical customer spends $61 per month on local and long-distance service.” A sample of 12 subscribers revealed the following amounts spent last month.
$65
$64
$65
$67
$58
$64
$67
$62
$64
$59
$55
$69
What is the point estimate of the population mean? (Round your answer to 3 decimal places.)
Develop a 98% confidence interval for the population mean. (Use t Distribution Table.) (Round your answers to 3 decimal places.)
Warren County Telephone Company claims in its annual report that “the typical customer spends $61 per month on local and long-distance service.” A sample of 12 subscribers revealed the following amounts spent last month.
Explanation / Answer
a) Point Estimate of population mean = (65+64+65+67+58+64+67+62+64+59+55+69)/12 = 63.250
b) Standard deviation = 4.092676
Margin of error = (T.INV(0.99,11)*4.092676)/Sqrt(12) = 3.211285
98% Interval
(63.250-3.211285,63.250+3.211285)
= (60.039, 66.461)
c) Yes, it is reasonable because $61 is contained in this interval
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