Question

The Johnson tire company measures their tire stems for cracks. They produce 300 tires a month and record the defective rate for each day's production.

Below are the results of this month's tests.

Day	Fraction Defective
1	0.01
2	0.08
3	0.11
4	0.03
5	0.09
6	0
7	0.07
8	0.02
9	0.05
10	0.02
11	0.04
12	0
13	0.08
14	0.06
15	0
16	0.09
17	0.02
18	0.11
19	0.01
20	0.04
21	0.09
22	0.1
23	0.05
24	0.03
25	0.08
26	0.07
27	0.1
28	0.02
29	0.01
30	0.13

Determine the 3 sigma UCL.

0.083

0.063

0.103

0.093

0.073

Previous

Answer 1

The correct answer is 0.093 .  

Day	Fraction Defective
1	0.01
2	0.08
3	0.11
4	0.03
5	0.09
6	0
7	0.07
8	0.02
9	0.05
10	0.02
11	0.04
12	0
13	0.08
14	0.06
15	0
16	0.09
17	0.02
18	0.11
19	0.01
20	0.04
21	0.09
22	0.1
23	0.05
24	0.03
25	0.08
26	0.07
27	0.1
28	0.02
29	0.01
30	0.13
	Total = 1.61

Mean fraction defetive = 1.61 30

Mean fraction defetive = 0.05367

Standard deviation =

Standard deviation = 0.0130

UCL =

UCL = 0.05367 + 3 * 0.0130

UCL = 0.093