Sandy Grey Ltd is in the process of deciding whether or not to revise its line of mobile phones which it manufactures and sells. Their sole market is large corporations and they have not as yet focused on the retail sector. They have estimated that the revision will cost £220,000. Cash flows from increased sales will be £80,000 in the first year. These cash flows will increase by 5 per cent per year. The firm estimates that the new line will be obsolete 5 years from now. Assume the initial cost is paid now and all revenues are received at the end of each year. If the company requires a 10 per cent return for such an investment, should it undertake the revision? Use three investment evaluation techniques to arrive at your answer.