You decide to implement a statistical process control mechanism for your exam studies. Specifically, you decide to solve many practice problems in OM during the days leading up to the exam. On each working day of the week, you noted the time you took in solving four random problems among all the problems you solved during that day. The data collected by you is shown in the table below (all figures are in minutes). Is your problem-solving process in control? Explain your answer and suggest an appropriate action that you might need to take. Use an X-bar chart to justify. No need to draw the chart.

\\begin{tabular}{|c|c|c|c|c|} \\hline Monday & Tuesday & Wednesday & Thursday & Friday \\\\ \\hline 20 & 19 & 20.4 & 18 & 19.5 \\\\ \\hline 21 & 19.8 & 22 & 22 & 36 \\\\ \\hline 20.5 & 20 & 19.8 & 21.5 & 20.6 \\\\ \\hline 21.4 & 20.1 & 21.2 & 22.5 & 25 \\\\ \\hline \\end{tabular}