During one month, a company processed 51,000 invoices for Alpha Corp, 49,000 for Beta Corp, and 25,000 for Gamma Corp. Of these, 510 of the Alpha, 525 of the Beta, and 480 of the Gamma invoices had to be reprocessed for errors. What is the overall defect rate and the sigma level for all of the combined batches? For each individual batch? Solution DPMO is Defects per Million Operations. .

1. During one month, a company processed 51,000 invoices for Alpha Corp, 49,000 for Beta Corp,
and 25,000 for Gamma Corp. Of these, 510 of the Alpha, 525 of the Beta, and 480 of the Gamma
invoices had to be reprocessed for errors. What is the overall defect rate and the sigma level for
all of the combined batches? For each individual batch?
Solution
DPMO is Defects per Million Operations.
Company Defects Invoices DPMO Appx Sigma
Alpha 510 51000 10000 4.2
Beta 525 49000 10714 4.2
Gamma 480 25000 19200 3.4
Overall 1515 125000 39914 3.1