Determine the upper and lower control limits for the fraction of retests using two-sigma limits

A medical facility does MRIs for sports injuries. Occasionally a test yields inconclusive results and must be repeated. Using the following sample data and n = 192.

SAMPLE

1

2

3

4

5

6

7

8

9

10

11

12

13

  Number of retests

1

2

2

0

1

1

2

0

2

7

3

1

2

a.

Determine the upper and lower control limits for the fraction of retests using two-sigma limits. (Do not round intermediate calculations. Round your final answers to 4 decimal places. Leave no cells blank - be certain to enter "0" wherever required.)

  UCL

[removed]  

  LCL

[removed]  

b.

Is the process in control?