Statistics

Statistics

Freshly painted autos are inspected for blemishes.  The company has established that the process average that meets their desired quality level is 8 blemishes per sample during the inspection process.  Following are the results for inspecting 20 groups of 10 cars at random during a week-long period.

Sample    Blemishes    Sample    Blemishes
1    8    11    6
2    12    12    8
3    9    13    9
4    11    14    15
5    6    15    7
6    12    16    10
7    10    17    11
8    8    18    12
9    14    19    9
10    7    20    6

Construct a c -chart using Z = 3.00 and determine if the painting process is in control.