Confidence Intervals
Point estimate ± margin of error for the population mean.
n ≥ 30 → use z = 1.96 (normal)
95% CI for μ
64.08 ≤ μ ≤ 71.92
margin = 1.96 × 12/√36 = 3.92
Interpretation: if we repeated this experiment many times, about 95% of the intervals we build would capture the true mean. The interval widens as confidence grows and shrinks as n grows (√n in the denominator).