4. A hospital does tests for patients. Occasionally a test yields inconclusive results and must be repeated. Using samples of 100 tests. It is been found the following: (calculate to three decimal places) (6 marks) 1 2 3 4 Sample NO. of retests 4 2 5 9 a. If the true fraction defective for this process is unknown, using two sigma control limits, is the process in control? b. Assuming a fraction defective of 2 percent, using 3 sigma control limits. Is the process in control