Question 8.158

electricmiles

61. Electric Cars. The accompanying table shows the miles-per-gallon equivalent (MPGe) for five electric cars, as reported by www.hybridcars.com in 2014.

Electric Vehicle MPGe
Tesla Model S 89
Nissan Leaf 99
Ford Focus 105
Mitsubishi i-MiEV 112
Chevrolet Spark 119
  1. Use technology to construct a normal probability plot of MPGe. Confirm that the distribution is normal.
  2. Find for a confidence interval with 90% confidence.
  3. Compute and interpret the margin of error for a confidence interval with 90% confidence.
  4. Construct and interpret a 90% confidence interval ( interval) for the population mean mileage.

8.2.61

(a)

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Acceptable normality. (b) (c) MPGe. We can estimate the population mean mileage to within 11.0 MPGe with 90% confidence.

(d) (93.8, 115.8). We are 90% confident that μ, the population mean mileage, lies between 93.8 MPGe and 115.8 MPGe.