In its Fuel Economy Guide for 2014 model vehicles, the Environmental Protection
ID: 3252512 • Letter: I
Question
In its Fuel Economy Guide for 2014 model vehicles, the Environmental Protection Agency gives data on 1160 vehicles. There are a number of high outliers, mainly hybrid gas-electric vehicles. If we ignore the vehicles identified as outliers, however, the combined city and highway gas mileage of the other 1134 vehicles is approximately Normal with mean 22.2 miles per gallon (mpg) and standard deviation 5.2 mpg. The quintiles of any distribution are the values with cumulative proportions 0.20, 0.40, 0.60, and 0.80. what are the quintiles of the distribution of gas mileage? (Round your answers to one decimal place.) What is the first quintile of the distribution of gas mileage? what is the second quintile of the distribution of gas mileage? What is the third quintile of the distribution of gas mileage? What is the fourth quintile of the distribution of gas mileage? You may need to use the appropriate Appendix Table to answer this question.Explanation / Answer
The z values for each of these quintiles are -0.843,-0.253,+0.253 and +0.843
multiplied by the sd, they are -4.38,-1.32,1.32, and 4.38
rounding to the answer
z=(value-mean)/sd
the quintiles are (units are mpg)
17.82
20.88
23.52
26.58