Answer
$X_{0.995}^2=2.603$
$X_{0.005}^2=26.757$
Work Step by Step
$n=12$. So:
$d.f.=n-1=11$
$level~of~confidence=(1-α).100$%
$99$% $=(1-α).100$%
$0.99=1-α$
$α=0.01$
$X_{1-\frac{α}{2}}^2=X_{0.995}^2=2.603$
(According to Table VII, for d.f. = 11 and area to the right of the critical value = 0.995)
$X_{\frac{α}{2}}^2=X_{0.005}^2=26.757$
(According to Table VII, for d.f. = 11 and area to the right of the critical value = 0.005)
