If the mean of a dataset is 25 and its standard deviation is 1.6, then. 1  68% of the values in the dataset will lie between MEAN-1SD (25-1.6=23.4) and MEAN+1SD (25+1.6=26.6) 2  99% of the values will lie between MEAN-3SD (25-4.8=20.2) and MEAN+3SD (25+4.8=29.8).
For the first time, during the Classical period most of the important stylistic advances that occurred can be observed most clearly in the instrumental forms: the symphony, concerto, sonata, and in instrumental chamber music (e.g., the Beethoven string quartets).
This is particularly true in the music written in the early part of the period. The Classical era was an era of formality. The music was characterized by careful attention to form and by elegance and restraint. The formal structure was based on the use of thematic development and harmonic structure.