A z-score equal to 0 represents an element equal to the mean. ... A z-score equal to -1 represents an element that is 1 standard deviation less than the mean; a z-score equal to -2, 2 standard deviations less than the mean; etc.
We have to rewrite the expression so that it has no denominator. For example: 1 / x = x^(-1) 1/8 = 8^(-1); 1/x^(4) = x^(-4); 1/y^(3) = y^(-3); 1/z = z^(-1).
