7. An NTN-F that matures on Jan/01/2025 and pays semiannual interest was purchased on May 05/2022 for R$1057 (use ANBIMA's Holidays spreadsheet to calculate business days). Answer: a. What is the gross annual rate of return on this investment? b. Suppose that on Apr 3, 2023 the NTN-F price changed to R$920. What would be the new gross annual rate of return on this investment? c. Calculate the duration of NTN-F on 05/May/2022 and 03/Apr/2023. Explain the possible reasons for the difference between the values obtained from the duration. d. Calculate the modified duration of NTN-F on 05/May/2022 and 03/Apr/2023. Use the calculated modified durations to project the NTN-F price if the interest rate increases 100 basis points, and if the interest rate decreases 100 basis points. Were the price changes the same for the increase and decrease?