Chapter 14, Problem 15QP

For each scenario suggest a control that could be used to reduce the risk. Entering negative values for order quantity in a sales order  Selling to a customer with an overdue account  Ordering from a non-existent supplier  Paying for goods that have not been received  Entering an alphanumeric customer ID when the business policy is for numeric customer IDs  Misappropriation of goods by receiving staff, who also maintain inventory records  Ordering too much of a product   8. You are required to list and explain three advantages of computer-executed control activities compared to manually executed control activities.

1. Three hundred identical cathode ray tubes (CRTS) placed into service simultaneously on January 1, 1976, experienced the following numbers of failures through December 31, 1988: 1983 Year Number of failures 1984 1985 1986 1987 1988 13 19 16 34 21 38 Assume that there were no failures before 1983. a. Based on these data, estimate the cumulative distribution function (CDF) of a CRT chosen at random. Using the results of part (a), estimate the probability that a CRT chosen at random 13.1 Reliability of a Single Component 753 b. Lasts more than 5 years. c. Lasts more than 10 years. d. Lasts more than 12 years. e. That has survived for 10 years fails in the 11th year of operation.

Fearless Inc. has designed and tested 400 Super Sucker Vacuum Cleaner models. All of them were operated for 1,000 hours at Lubbock's Fearless test facility.  Out of all the vacuums 2 of them failed during the test.  One of them after 900 hours and the other after 500 hours. What is this product estimated Mean Time Between Failures?