Answer
$x_1=x_2=x_3=x_4=x_5=x_6=x_7=x_8=15$
There is no other possibility.
Work Step by Step
$x̅=\frac{15+15+15+15+15+15+15+15}{8}=\frac{120}{8}=15$
$s=\sqrt {\frac{Σ(x_i-x̅)^2}{n-1}}=\sqrt {\frac{(15-15)^2+(15-15)^2+(15-15)^2+(15-15)^2+(15-15)^2+(15-15)^2+(15-15)^2+(15-15)^2}{8-1}}=\frac{0}{7}=0$
