In its Fuel Economy Guide for 2016 model vehicles, the Environmental Protection Agency provides data on 11701170 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 11461146 vehicles is approximately Normal with mean 23.023.0 miles per gallon (mpg) and standard deviation 4.94.9 mpg. The quartiles of any distribution are the values with cumulative proportions 0.250.25 and 0.75.0.75. They span the middle half of the distribution. What is the first quartile of the distribution of gas mileage? give your answer rounded to two decimal places. Q1=?     What is the third quartile of the distribution of gas mileage?  give your answer rounded to two decimal places. ?3=?

Definition Definition Measure of central tendency that is the average of a given data set. The mean value is evaluated as the quotient of the sum of all observations by the sample size. The mean, in contrast to a median, is affected by extreme values. Very large or very small values can distract the mean from the center of the data. Arithmetic mean: The most common type of mean is the arithmetic mean. It is evaluated using the formula: μ = 1 N ∑ i = 1 N x i Other types of means are the geometric mean, logarithmic mean, and harmonic mean. Geometric mean: The nth root of the product of n observations from a data set is defined as the geometric mean of the set: G = x 1 x 2 ... x n n Logarithmic mean: The difference of the natural logarithms of the two numbers, divided by the difference between the numbers is the logarithmic mean of the two numbers. The logarithmic mean is used particularly in heat transfer and mass transfer. ln x 2 − ln x 1 x 2 − x 1 Harmonic mean: The inverse of the arithmetic mean of the inverses of all the numbers in a data set is the harmonic mean of the data. 1 1 x 1 + 1 x 2 + ...