College X is concerned about their employees making use of their email for non-business purposes. A random sample of 400 e-mails discovered 60 messages that were not business related. The 90% confidence interval for the population proportion is:
A) 0.104 to 0.196
B) 0.115 to 0.185
C) 0.148 to 0.252
D) 0.121 to 0.179
E) 0.186 to 0.254

Question

Quizplus · Accepted Answer

The sample proportion is 60/400 = 0.15. Using the formula for the confidence interval for a proportion, and a Z-score for 90% confidence (1.645), the interval is calculated as 0.15 ± 1.645 * sqrt((0.15*(1-0.15))/400), which results in approximately 0.121 to 0.179.

College X Is Concerned About Their Employees Making Use of Their