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.
For a long time, catgut was the most common material for the strings of harps, lutes, violins, violas and cellos, acoustic guitars and other stringed musical instruments, as well as older marching snare drums. Most musical instruments produced today use strings with cores made of other materials, generally steel or synthetic polymer.