Question

During one month, MegaInvoice Company (MIC) processed 25,000 invoices for Alpha Corp, 25,000 for Beta Corp, and 15,000 for Gamma Corp. Of these, 180 of the Alpha, 220 of the Beta, and 100 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? USE FORMULAS NOT NORMS'INV FUNCTION and SHOW STEPS PLEASE

Answer 1

Below is the required defect rate -

	Alpha Corp	Beta Corp	Gamma Corp	Overall
Total Invoices (n)	25000	25000	15000	65000
Defect	180	220	100	500
Defect Rate p (Defect/Total Invoices)	0.00720	0.00880	0.00667	0.00769
1-p	0.99280	0.99120	0.99333	0.99231
Sigma Level (    sqrt(p*(1-p)/n)         )	0.00053	0.00059	0.00066	0.00034

From above -

Overall Defect Rate = 0.00769

Overall Sigma Level = 0.00034