The formula for a confidence interval for a proportion is:
p ± z*√(p*(1-p)/n)
where p is the sample proportion, z is the z-score corresponding to the desired confidence level, and n is the sample size.
For a 90% confidence interval, the z-score is 1.645.
Plugging in the values, we get:
0.3 ± 1.645*√(0.3*(1-0.3)/684)
Simplifying:
0.3 ± 0.0493
The lower bound of the confidence interval is:
0.3 - 0.0493 = 0.2507
Rounded to four decimal places:
0.2507
In a random sample of 684 observations,
p-bar = 0.3. What lower bound of a 90% confidence interval for p?
Round to four decimal places for all your calculations, including the FINAL answer.
1 answer