We have the formula to calculate the annual percentage yield that let us compare different investment or interest rates with different capitalization periods, transforming them in a consistent annual measure.
The formula is:
where r: nominal annual interest rate and n: subperiod of capitalization (number of capitalizations in a year).
In this case, with an interest rate of 3% (r=0.03) monthly compounded (n=12) we can calculate the APY as:
Answer: the APY for this investment is 3.04%.