One year thomas had the lowest ERA​ (earned-run average, mean number of runs yielded per nine innings​ pitched) of any male pitcher at his​ school, with an ERA of 2.67 . ​Also, sarah had the lowest ERA of any female pitcher at the school with an ERA of 2.99. For the​ males, the mean ERA was 4.996 and the standard deviation was 0.948. For the​ females, the mean ERA was 3.781 and the standard deviation was 0.716. Find their respective​ z-scores. Which player had the better year relative to their​ peers, or ​? ​(Note: In​ general, the lower the​ ERA, the better the​ pitcher.) what is Thomas had an ERA with a​ z-score of _. Sally had an ERA with a z-score of _.

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 + ...