A poll asked 956 licensed drivers whether they supported a nationwide lowering of the drunk driving limit to 0.08% BAC (blood alcohol content), and 72% said they did. Estimate a 95% confidence interval for actual percentage among all licensed drivers.
A) 70.5% to 73.5%
B) 69% to 75%
C) 71.8% to 72.2%
D) 70% to 74%

Question

Quizplus · Accepted Answer

The confidence interval is calculated using the formula for a proportion: p ± Z*(√(p(1-p)/n)), where p is the sample proportion (0.72), Z is the Z-score for 95% confidence (approximately 1.96), and n is the sample size (956). This calculation results in an interval of approximately 69% to 75%.

A Poll Asked 956 Licensed Drivers Whether They Supported a Nationwide