The term "snowstorms of note" applies to all snowfalls over 6 inches. The snowfall amounts for snowstorms of note in Utica, New York, over a four year period are as follows:
7.1, 9.2, 8.0, 6.1, 14.4, 8.5, 6.1, 6.8, 7.7,
21.5, 6.7, 9.0, 8.4, 7.0, 11.5, 14.1, 9.5, 8.6
What is the standard deviation for these data to the nearest hundredth?
[Space is provided for optional work.]