Unformatted text preview: 3. 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 60 of these accounts were delinquent.
a. What is the 95% conﬁdence interval for the proportion of all delinquent customer accounts at this manufacturing company? Explain the meaning of the interval. 1). What is the margin of error for the interval in part (a)? c. Determine the sample size needed in order to be 99% conﬁdent that the sample proportion of the
delinquent customer accounts is within .03 of the true proportion of all delinquent accounts for this company. ...
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- Spring '08