Answer
$d ̅=-0.2$
$s_d=0.526$
Work Step by Step
$d ̅=\frac{∑d_i}{n}=\frac{0.2-0.5+0.2+0.6-0.6-0.5-0.8}{7}=-0.2$
$s_d=\sqrt {\frac{∑(d_i-d ̅)^2}{n-1}}=\sqrt {\frac{[0.2-(-0.2)]^2+[-0.5-(-0.2)]^2+[0.2-(-0.2)]^2+[0.6-(-0.2)]^2+[-0.6-(-0.2)]^2+[-0.5-(-0.2)]^2+[-0.8-(-0.2)]^2}{7-1}}=0.526$
