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.
There are 4 types: Spinet - With its height of around 36 to 38 inches, and an approximate width of 58 inches, spinets are the smallest of the pianos. Given its size, it is the popular choice of many people who live in limited living spaces such as apartments.