In: Statistics and Probability
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. $63 $67 $65 $68 $60 $65 $68 $62 $64 $63 $54 $67
a. What is the point estimate of the population mean? (Round your answer to 3 decimal places.)
Estimated population mean $:
b. Develop a 98% confidence interval for the population mean. (Use t Distribution Table.) (Round your answers to 3 decimal places.)
Confidence interval for the population mean $ and $
c. Is the company's claim that the "typical customer" spends $61 per month reasonable?
Yes No
From the given sample data: n=12 , ,
The sample mean is ,
The sample standard deviation is ,
The critical value is ,
; From t-table
a) The point estimate of the population mean is =63.833
b) The 98% confidence interval for the population mean is ,
c) We have , Hypothesis: Vs
Here , the value $61 lies in the given 98% confidence interval
Therefore , failto reject Ho.
Conclusion : Yes, there is sufficient evidence to support the claim that the "typical customer" spends $61 per month reasonable.