Question

ris poll asked a random sample of 1,015 adults nationwide the following question: are you afraid of being alone in an elevator? 10% of the people in the in the sample answered yes. the se of the sample % is about 0.94%. a) an approximate 95% confidence interval for the percentage of all american adults who are afraid of being alone in an elevator is closest to incorrect 9.94%-10.06% correct: 8.12%-11.88%

Answer 1

Answer: The correct answer is 8.12%-11.88%.

We can use the formula for a confidence interval for a proportion:

p ± z*SE

where p is the sample proportion, z* is the z-score corresponding to the desired level of confidence (in this case, 1.96 for a 95% confidence interval), and SE is the standard error of the proportion.

SE = sqrt(p*(1-p)/n) = sqrt(0.1*0.9/1015) = 0.0094

Plugging in the values, we get:

0.1 ± 1.96*0.0094

= 0.1 ± 0.0184

So the 95% confidence interval is (0.0816, 0.1184), which is equivalent to 8.12%-11.88%.

Explanation: