In the cash balance model from Example 12.6, the timing is such that some receipts are delayed by 1 or 2 months, and the payments for materials and labor must be made a month in advance. Change the model so that all receipts are received immediately, and payments made this month for materials and labor are 80% of sales this month (not next month). The period of interest is again January to June. Rerun the simulation, and comment on any differences between your outputs and those from the example.