Please show step by step so I can follow along. See attached question

Question 4: Sensitivity Graphs (10 Marks) A manufacturing firm has decided to plan for the purchase of a pickup truck several years from now. At that time, the company estimates that they will need $72,000 and has decided to set aside a uniform amount of money at the end of every month to save up for this need. It believes it is possible to set aside $1,180 per month at 9% compounded monthly interest. It wishes to know how long it will take to save $72,000 and how sensitive this result is to a 5% and 10% increase or decrease in both the amount saved per month and in the interest rate. a) As a base case, determine how many months it will take to save 572,000. b) Construct a sensitivity graph to illustrate how the number of months change as a function of % change. c) This plan is most sensitive to which variable