Acme (NC) has long used a central telephone

Acme (NC) has long used a central telephone/Internet customer support center based in Jamaica. Data collected by the center show that last year, all but five (5) of every 100,000 calls/accesses received by the center were satisfactorily (to the customer) handled within the targeted time of two hours.
1. What is the highest Sigma rating that the Jamaica customer support center can claim? Show how you reached this rating.
Answer. You must first find the defect percentage by calculating the number defects divided opportunities.
5 (defects)/100,000 (calls) x number of units = 0.00005.
Next, you need to calculate the sigma level that correlates to this number called DPO ( Defect Per Opportunity).
The NORMSINV in excel can be used to get this number or a sigma level table can be used.
NORMSINV x 0.00005= 3.89
(Attached is an excel file showing how this was calculated).
Last, a 1.5 sigma level is added for deviation in shift times. So, the call center sigma level is 5.39.
(3.89 + 1.5= 5.39).
2 Q. After Acme Mexico City (AMC) begins operations next year, should the Jamaica center support AMC’s customers?
@ Answer-If all factors are held constant, I would recommend that the Jamaica call center continue to support Acme’s customers. According to sigma levels table, 5.38 is consider a good score. However, it also depends on Acme’s standard of what they consider is a high score. Acme might consider 5.38 to be a low score and only willing to accept a top level of 7 or 8.