A sample of rental cars showed the following annual mileage (in thousands of miles) 46.768 34.813 69.194 36.927 57.666 36.003 42.961 37.194 47.750 41.738 44.239 34.052 31.731 54.661 30.928 47.847 31.286 38.813 40.166 32.905 42.057 49.834 47.556 37.729 22.120 40.822 41.104 62.399 32.550 43.558 9 The sample mean mileage is, a 40.990 thousand b 41.912 thousand c 42.855 thousand d 43.819 thousand

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 + ...