Problem 10-7 The postmaster of a small western town receives a certain number of
ID: 424670 • Letter: P
Question
Problem 10-7
The postmaster of a small western town receives a certain number of complaints each day about mail delivery.
a.Determine two-sigma control limits using the above data. (Round your intermediate calculations to 4 decimal places and final answers to 3 decimal places. Leave no cells blank - be certain to enter "0" wherever required. Round up any negative control limit value to zero.)
b. Is the process in control?
No
Yes
DAY 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Number of complaints 4 10 14 8 9 6 5 12 15 7 6 4 2 10Explanation / Answer
Total complaints= (4+10+14+8+9+6+5+12+15+7+6+4+2+10)=112
CL= Total complaints / total samples = 112/14=8
UCL = CL+z(CL)0.5 = 8+2*80.5= 13.66
LCL= CL-z(CL)0.5 = 8-2*80.5= 2.34
The process is not in control as some data is not within LCL and UCL