I need help with question 7.36. I looked at the solution for this question and there was a thumbs down for it and I don't know if that person did that question wrong

204 Chapter 7 7.36 Profit and loss (in $1000 units) associated with the sale of a vision-guided machine tool loading sys- tem and the resulting NCF amounts are recorded. (a) Use sign-change rules to determine the possi- ble number of i* values. (b) Find all i* values be- tween 0 and 100%. (c) If the required MARR for the company is 15% per year, how small can the gradient be for years 3 through 6? Year Cash Flow, $ -5,000 -10,100 4,500 6,500 8,500 10,500 12,500 7.4 Removing Multiple i* Values 7.37 For the net cash flow series, (a) determine the number of possible i* values using the two sign tests, (b) find the EROR using the MIRR method with an investment rate of 20% per year and a bor- ADD 204 Chapter 7 7.36 Profit and loss (in $1000 units) associated with the sale of a vision-guided machine tool loading sys- tem and the resulting NCF amounts are recorded. (a) Use sign-change rules to determine the possi- ble number of i* values. (b) Find all i* values be- tween 0 and 100%. (c) If the required MARR for the company is 15% per year, how small can the gradient be for years 3 through 6? Year Cash Flow, $ -5,000 -10,100 4,500 6,500 8,500 10,500 12,500 7.4 Removing Multiple i* Values 7.37 For the net cash flow series, (a) determine the number of possible i* values using the two sign tests, (b) find the EROR using the MIRR method with an investment rate of 20% per year and a bor- ADD