IV. Island Airlines Inc. needs to replace a short-haul commuter plane on one of its busier routes. Two aircraft are on the market that satisfy the general requirements of the route. One is more expensive than the other but has better fuel efficiency and load-bearing characteristics, which result in long-term profitability. The useful life of both planes is expected to be about seven years, after which time both are assumed to have no value. Cash flow projections for the two aircraft follow: a. Calculate the payback period for each plane and select the best choice. (10 pts) b. Calculate the IRR for each plane and select the best option. (20 pts) c. Calculate the NPV, assuming cost of capital of 6%. (15 pts)