The Tillamook County Creamery Association manufactures Tillamook Cheddar Cheese. It sells the cheese in four? varieties: aged 2? months, 9? months, 15? months, and 2 years. At the shop in the? dairy, it sells 2 pounds of each variety for the following? prices: $ 7.00?, $ 9.50?, $ 10.95?, and $ 12.00?, respectively. Consider the cheese? maker's decision whether to continue to age a particular? 2-pound block of cheese. At 2? months, he can either sell the cheese immediately or let it age further. If he sells it? now, he will receive $ 7.00 immediately. If he ages the? cheese, he must give up the $ 7.00 today to receive a higher amount in the future. What is the IRR? (expressed in percent per? month) of the investment of giving up $ 70.00 today by choosing to store 20 pounds of cheese that is currently 2 months old and instead selling 10 pounds of this cheese when it has aged 9? months, 6 pounds when it has aged 15? months, and the remaining 4 pounds when it has aged 2? years?
The IRR is _____?% per month. ?(Round to two decimal? places.)