Answer
$X_0^2\gt X_{1-α}^2$: null hypothesis is rejected.
There is enough evidence to conclude that Derrick Rose is more consistent than other shooting guards.
Work Step by Step
$H_0:~σ=8.3$ versus $H_1:~σ\lt8.3$
$X_0^2=\frac{(n-1)s^2}{σ_0^2}=\frac{(25-1)6.7^2}{8.3^2}=15.639$
Left-tailed test:
$n=25$
$d.f.=n-1=24$
$X_{1-α}^2=X_{0.90}^2=15.659$
(According to Table VII, for d.f. = 24 and area to the right of critical value = 0.90)
Since $X_0^2\lt X_{1-α}^2$, we reject the null hypothesis.
