Thus, one sense in which the tone is a mean is that, as a frequency ratio, it is the geometric mean of the major tone and the minor tone: , equivalent to 193.157 cents: the quarter-comma whole-tone size. However, any intermediate tone qualifies as a "mean" in the sense of being intermediate, and hence as a valid choice for some meantone system.
Thus, one sense in which the tone is a mean is that, as a frequency ratio, it is the geometric mean of the major tone and the minor tone:  equivalent to 193.157 cents: the quarter-comma whole-tone size. However, any intermediate tone qualifies as a "mean" in the sense of being intermediate, and hence as a valid choice for some meantone system.