A gold mine can be purchased for $100 million. Determine the ROR if this investment for the following cases. The estimated useful life of the mine is 10 years. a) the annual benefit is $10 million b) The annual benefit is $10 million the first year and increases by 10% per year. c) The annual benefit is $20 million d) The annual benefit is $30 million e) If the first year benefit is $15 million, at what percentage must the benefits increase to give a ROR of 20%