Restaurant Drive-Through Service Times Service Times (seconds) Restaurant X 122 110 110 Restaurant Y 80 181 335 144 04 158 202 103 303 107 157 143 180 118 233 230 118 145 104 183 157 140 270 207 158 181 68 178 357 101 187 305 97 134 135 123 148 148 248 232 248 235 238 187 78 148 127 150 108 137 02 108 157 113 128 217 242 140 173 170 122 205 130 140 121 220 134 300 176 184 177 113 195 220 200 107 144 141 131 140 108 148 162 85 145 127 105 141 180 55 100 153 175 122 122 174 110

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 + ...