The data in the following table represent individual observations on molecular weight taken hourly from a chemical process. The target value of molecular weight is 1,050 and the process standard deviation is thought to be about = 25.

Observation Number	x	Observation Number	x
1	1,045	11	1,139
2	1,055	12	1,169
3	1,037	13	1,151
4	1,064	14	1,128
5	1,095	15	1,238
6	1,008	16	1,125
7	1,050	17	1,163
8	1,087	18	1,188
9	1,125	19	1,146
10	1,146	20	1,167

a. Set up a tabular CUSUM for the mean of this process. Design the CUSUM to quickly detect a shift of 1, using h = 5.

b. At what point did the assignable cause that sent the process out of control occur (this is not the same as when it actually went out of control)?