Last year, a consumer affairs investigator recorded the repair cost for 14 randomly selected iPhones.  They found a sample mean of $187.52 and standard deviation of $29.49.  They are also assuming that the population -- that is, the repair cost of all iPhones -- is approximately normal. Determine the 90% confidence interval for the mean repair cost for all iPhones. Show all relevant steps Express your final answer as an interval (value, value) and round to two decimal places as needed. If Apple (the manufacturer of iPhones) claimed that the mean repair cost of all iPhones last year was less than $170, would you believe their claim?  Give a reason using the information given and your results into support your answer.

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section10.4: Distributions Of Data
Problem 19PFA
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Last year, a consumer affairs investigator recorded the repair cost for 14 randomly selected iPhones.  They found a sample mean of $187.52 and standard deviation of $29.49.  They are also assuming that the population -- that is, the repair cost of all iPhones -- is approximately normal.

Determine the 90% confidence interval for the mean repair cost for all iPhones.

  • Show all relevant steps
  • Express your final answer as an interval (value, value) and round to two decimal places as needed.


If Apple (the manufacturer of iPhones) claimed that the mean repair cost of all iPhones last year was less than $170, would you believe their claim?  Give a reason using the information given and your results into support your answer.  

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