Q1. The internal auditing staff of a local manufacturing company performs a sample audit each quarter to estimate the proportion of accounts that are delinquent (more than 90 days overdue). For this quarter, the auditing staff randomly selected 400 customer accounts and found that 80 of these accounts were delinquent. What is the 95% confidence interval for the proportion of all delinquent customer accounts at this manufacturing company?
A. 0.1485 to 0.2515
B. 0.1608 to 0.2392
C. 0.1992 to 0.2008
D. 0.1671 to 0.2329
E. 0.1714 to 0.2286
Q2. The internal auditing staff of a local manufacturing company performs a sample audit each quarter to estimate the proportion of accounts that are current (between 0 and 60 days after billing). The historical records show that over the past 8 years 70 percent of the accounts have been current. Determine the sample size needed in order to be 95% confident that the sample proportion of the current customer accounts is within .02 of the true proportion of all current accounts for this company.
A. 1421
B. 1549
C. 1842
D. 2017
E. 3484