The standard deviation of n numerical data \(x_1,x_2,x_3,...,x_n\), With mean \(\overline{x}\) is equal to \(\sqrt{\frac{S}{n}}\), where S is the sum of the squared differences \((x_i- \overline{x})^2\), for \(1 ≤ i ≤ n\).

Each book that a bookstore sold last year was either new or used. The bookstore sold new books for $80 each and used books for $40 each. The standard deviation of the prices of the books sold last year was $16.

Quantity A	Quantity B
The fraction of the books sold last year that were new	\(\frac{1}{2}\)