SOLUTION: You are estimating the cost of engine overhauls. A sample of 99 repairs showed an average overhaul of 285 hours with a standard deviation of 60 hours. Calculate a 95% confidence in

Question 1050519: You are estimating the cost of engine overhauls. A sample of 99 repairs showed an average overhaul of 285 hours with a standard deviation of 60 hours. Calculate a 95% confidence interval for the average overhaul. (Carry intermediate calculations to three decimal places.)

268.20 ≤ μ ≤ 301.80

273.18 ≤ μ ≤ 296.82

271.00 ≤ μ ≤ 299.00

281.61 ≤ μ ≤ 288.39

Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!



Hi  

 CI	z = value

90%	z =1.645

92%	z = 1.751

95%	z = 1.96

98%	z = 2.326

99%	z = 2.576

95% Confidence Interval:  z = 1.96,  n = 99, m = 285

ME =

ME = 1.96*60/sqrt(99) = 11.82

285 - ME <  < 285+ ME

285 - 11.82 <  < 285+ 11.82

273.18 ≤ μ ≤ 296.82 

 

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