Standard deviation is the square root of variance, but variance is given by mean, so divide by number of samples. That is : 38.5/10 = 3.58. But standard deviation equals the square root of variance, so SD = the square root of 3.85 which is 1.96.
The virginal(s): The virginal, also called virginals, usually has a rectangular case with the keyboard across the wide side. As with the spinet, the strings run side-to-side relative to the player. Again, it saves on wallspace, and again they rate their own FAQ. Virginals were fairly early, 15th and16th centuries.
A Stradivarius is one of the violins, violas, cellos and other string instruments built by members of the Stradivari (Stradivarius) family, particularly Antonio Stradivari, during the 17th and 18th centuries. Stradivarius made in the 1680s, or during Stradivari's Long Pattern period from 1690 to 1700, could be worth hundreds of thousands to several million U.S. dollars at today's prices.