A tire manufacturer has been concerned about the number of defective tires found recently. In order to evaluate the true magnitude of the problem, a production manager selected 20 random samples of 50 units each for Inspection. The number of defective tires found in each sample are as follows: 1 5 Defective 0 7 1 1 Sample Defective Sample Defective 8 1 15 1 16 17 18 MGMT 3106: Management Science and Operations Management 3 10 11 0 2 12 13 14 2 3 19 20 Total= 0 25 a) Calculate the p-bar, standard deviation, upper and lower control limits. Show all calculations. (You may use Excel tools to verify your answers). b) Plot the p-chart. (You may use Excel tools to plot the charts.) c) Based on the p-chart, discuss whether the process in statistical control or not.