Five data entry operators work at the data processing department of the Birmingham Bank. Each day for 30 days, the number of de
fective records in a sample of 300 records typed by these operators has been noted, as follows:
Sample No.
No. Defectives
Sample No.
No. Defectives
Sample No.
No. Defectives
1
8
11
7
21
17
2
4
12
5
22
13
3
19
13
16
23
6
4
10
14
3
24
6
5
12
15
12
25
13
6
9
16
8
26
11
7
11
17
13
27
15
8
10
18
4
28
7
9
6
19
18
29
13
10
14
20
17
30
4
a) Establish 3σ upper and lower control limits.
UCLp = (enter your response as a number between 0 and 1, rounded to three decimal places).
LCPp =(enter your response as a number between 0 and 1, rounded to three decimal places).
b) Why can the lower limit not be a negative number? (I actually know this one but I wanna get all the points down)
c) The industry standards for the upper and lower control limits are 0.10 and 0.01, respectively. What does this imply about Birmingham Bank's own standards?
b) Hence, Lower control limit cannot be a negative number as percent defective cannot be a negative number. As such, No. Percent of defective records cannot be a negative number.
To convert a decimal to a percent, multiply the decimal by 100, then add on the % symbol. An easy way to multiply a decimal by 100 is to move the decimal point two places to the right.
