Chapter 9 - Section 9.2 - Assess Your Understanding - Applying the Concepts - Page 452: 50a

Lower Bound = 46.06, Upper Bound = 54.44

Here we have n = 12, df = n-1 = 11, x̅ = 50.25 and s = 6.6 Confidence = 95% α = 1 - 0.95 = 0.05, α/2 = 0.025, $t_{α/2} = 2.201$ $E = 2.201 \times \frac{6.6}{\sqrt 12} = 4.19 $ $Lower Bound = x̅ - E = 50.25 - 4.19 = 46.06$ $Upper Bound = x̅ + E = 50.25 + 4.19 = 54.44$