Over the past several months, there have been a growing number of complaints from patients and staff about the long processing time of patient invoices. In order to verify complaints, the number of days taken to finish and mail invoices was recorded for 25 consecutive invoices as shown in Table 3. Use Excel to construct x and mR charts (attach outputs)

Table 3. Processing Time of Patient Invoices (Days)

Invoice	Day	Invoice	Day
1	28	14	31
2	26	15	27
3	29	16	27
4	28	17	26
5	32	18	31
6	34	19	32
7	34	20	32
8	35	21	29
9	27	22	30
10	31	23	32
11	24	24	31
12	28	25	33
13	31