Question

the national economy shrank in an annual rate of 8% per year for three consecutive years then the economy shrank by 24% over the three year. The economy actually shrank by what percentage over 3 year.

Answer 1

The economy is at a level that is (1 - 8%)³ = 0.778688 of the level it was at the beginning of the 3-year period. It has shrunk by

... 1 - 0.778688 ≈ 22.1%