Caculation of NPV and Sensitivity Analysis

"A. What other factors should be taken into account before Mississippi Delta Inc. makes a switch, assuming such is justifiable on an NPV basis. B. Sensitivity analysis involves varying the key assumptions, one at a time, and observing the effect on the key decisions criterion-such as profits or NPV. In the NPV analysis above, how could one carry out sensitivity analysis? (If you have a financial spreadsheet available, conduct a sensitivity analysis that varies the number of prompt payers who will pay I exactly 10 days and report your findings.) "