The data in p2data are the number of spelling errors detected from every 1000 words on a news Web site over 20 weeks.

a) What control chart is most appropriate for these data?

b) Using all the data, compute trial control limits for the chart in part (a), construct the chart and plot the data.

p2data

week	No. of spelling errors
1	3
2	6
3	0
4	5
5	9
6	5
7	2
8	2
9	3
10	2
11	1
12	6
13	9
14	8
15	6
16	4
17	13
18	3
19	0
20	7