3Calculate the internal rate of return of the investment, which for the first three years brings a positive flow of 2,600 PLN at the end of each year, and 1,800 PLN in half, one and a half and two and a half of the year. The investment amount is 10500 PLN. Please also calculate the profitability index for this investment. Use a discount rate of 10%. Comment the results and the entire investment (in the light of calculated above measures).