Answer
4.305
Work Step by Step
$6.2-10.5 = -4.3$
$12.8-10.5 = 2.3$
$7.6-10.5 = -2.9$
$15.4-10.5 = 4.9$
$variance = ((-4.3)^2 + 2.3^2 + (-2.9)^2 + 4.9^2)/4-1$
$variance =(18.49 + 4.69 + 8.41 + 24.01)/3$
$variance =18.5333$
$deviation =\sqrt 18.5333$
$deviation = 4.305$