Final answer:
Accuracy in costing can be affected by incorrect job numbers on documents, errors in bar coding, and misuse of computerized systems requiring employee numbers. All options listed can lead to costing problems.
Step-by-step explanation:
Problems with accurate costing occur when incorrect job numbers are recorded on source documents. Although bar coding and computerized systems such as an employee number verification can improve accuracy, the direct answer to the question is that all the aforementioned issues can lead to inaccuracies in costing.
When an employee records an incorrect job number, it can result in the wrong job being charged for materials or labor, causing an inaccuracy in the costing system. While bar coding generally increases the accuracy of tracking materials use, it can also contribute to problems if barcodes are incorrectly applied or scanned. Furthermore, computerized systems that require an employee number before allowing access to specific job information are a safeguard, but if the system is bypassed or the employee number is shared or misused, it can contribute to inaccuracies in job costing.