The following one-year "forward" rates exist for each of the years 2012-2016:

1/1/12 - 31/12/12 20.00%

1/1/13 - 31/12/13 25.00%

1/1/14 - 31/12/14 20.00%

1/1/15 - 31/12/15 20.00%

1/1/16 - 31/12/16 11.11%

Calculate the 1, 2, 3, 4, and 5 year spot rates as at 1/1/12. Accuracy to two decimal places is required.

Help to explain what kind of formula should we approach for this question. THanks!