six sigma in relation to process duration
Would it be possible to elaborate a little on the relation between six sigma quality requirement and process duration?
I am looking at the question that has 13 days of the PERT task duration estimate and 1 day as a standard deviation. The correct answer reads that the task can be completed from 7 to 19 days period. I don't really understand where 6 days duration deviation came from...
Any input is greatly appreciated.