4. (30 points) Consider the following cash flow diagram related to project ay of company X. The company in question can easily invest money at the rate of 10% (external investing rate) and borrow money at the rate of 5% (external borrowing rate). a) Determine the maximum number of internal rate of returns (IRRS). (5 points) b) Use IRR/ERR to decide if project ay is worthwhile for company X under MARR = 6%. (25 points) (You must use gradient and annuity factors!) 6:200 Yr 0 -300-500 100 -400 100 Z 300 -100 3 500 400 4 400 A 5 7 8 0 300 -700 - 300 Negative ci at Punder 1:5% 400 100 -200 400 -500 500 700 300 500 3 5 300 A