Why can't standard deviation be negative?

Enter the number of complex zeros for the polynomial function f(x) = x 4+ 5x² +6

Fred has a spinner that is split into four equal sections: red, blue, green, and yellow. fred spun the spinner 688 times. which of the following would be a good estimate of the number of times the spinner lands on the green section? a. 269 b. 603 c. 344 d. 189

|z| > (1/2) {-1/2, 1/2} {z|(-1/2) < z < (1/2)} {z|z < (-1/2) ∪ z > (1/2)}