A mining company has been exploring for some time in search of a gold vein. Finally, 27 months after the activities began, they found a deposit. The data of their costs are shown in the following table:

Month	Concept	Cost in millions
0	Purchase of equipment	102
1-15	Scan Monthly Maintenance	21
16-20	Scan Monthly Maintenance	25.5
20	additional equipment	62.8
21-27	Scan Monthly Maintenance	26.5
28	Reservoir evaluation	10.8
29	Cost of extraction and processing facilities	1005

Estimates made by experts indicate that it is possible to obtain a monthly quantity of metal with a value of $32 million, for a period of eight years from the 30th month; after eight years the sale would be exhausted. The salvage value of all facilities and equipment is estimated at 250 million. Determine the annual IRR of the investment over the 10 years and five months of the mining business.