Hi Jennifer.
You can't. To figure out a standard deviation, you need the original data that the mean was taken from.
For example, the mean of {0, 5, 10, 15, 20} is 10 and the std dev is
7.1. But the mean of {8, 9, 10, 11, 12} is also 10 and the std dev is
1.4.
Stephen La Rocque.>
