A random sample of 400 voters finds 240 support a ballot measure. Conditions for inference are met.
Which is the 95% confidence interval for the population proportion?
- A
(0.560, 0.640)
- B
(0.500, 0.700)
- C
(0.540, 0.660)
- Dcheck_circle
(0.552, 0.648)
Explanation
p̂ = 0.60. SE = sqrt(0.6·0.4/400) = 0.0245. ME = 1.96·0.0245 ≈ 0.048. CI: 0.60 ± 0.048 = (0.552, 0.648).