Chapter 9 - Section 9.3 - Assess Your Understanding - Vocabulary and Skill Building - Page 459: 10a

Lower Bound = 9.368, Upper Bound = 66

Here n = 10, df = n-1 = 9, $s^{2} = 19.8$, Confidence Interval = 95% α = 1 - 0.95 = 0.05, α/2 = 0.025, 1 - α/2 = 0.975 $χ2_{α/2} = 19.023$, $χ2_{1-α/2} = 2.700$ $\frac{(n-1)s^{2}}{χ2_{α/2}} < σ^{2} < \frac{(n-1)s^{2}}{χ2_{1-α/2}}$ $\frac{9 \times 19.8}{19.023} < σ^{2} < \frac{9 \times 19.8}{2.700}$ $ 9.368 < σ^{2} < 66$